CVE-2026-54512

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.

Red Hat Lightwell has released com.fasterxml.jackson.core:jackson-databind 2.17.3.rhlw-00013 with backported fixes for CVE-2026-83557, CVE-2026-54512, CVE-2026-54515, CVE-2026-19032, CVE-2026-77310, CVE-2026-54514, CVE-2026-59888, and CVE-2026-54513.

CVE-2026-83557: jackson-databind omits java.lang.Comparable from DefaultBaseTypeLimitingValidator's unsafe base types

CVE-2026-54512: jackson-databind: PolymorphicTypeValidator bypass via generic type parameters allows arbitrary class instantiation

CVE-2026-54515: jackson-databind: Case-insensitive deserialization bypasses per-property @JsonIgnoreProperties

CVE-2026-19032: jackson-databind resolves attacker-controlled URI schemes when deserializing java.nio.file.Path

CVE-2026-77310: jackson-databind: Eager DNS resolution (SSRF) still present in InetAddress deserialization (Incomplete fix for CVE-2026-54514)

CVE-2026-54514: jackson-databind: InetSocketAddress deserialization triggers eager DNS resolution (SSRF)

CVE-2026-59888: jackson-databind: @JsonIgnore on a Record property is bypassed with a PropertyNamingStrategy

CVE-2026-54513: jackson-databind: Array subtype allowlist bypass in BasicPolymorphicTypeValidator (allowIfSubTypeIsArray)

This patched artifact is a drop-in replacement for com.fasterxml.jackson.core:jackson-databind 2.17.3 from Maven Central.

Red Hat Lightwell has released com.fasterxml.jackson.core:jackson-databind 2.13.4.1-rhlw-00013 with backported fixes for CVE-2026-50193, CVE-2026-54512, CVE-2026-54513, and CVE-2026-54514.

CVE-2026-50193: jackson-databind: Deeply nested JsonNode throws StackOverflowError for toString()

CVE-2026-54512: jackson-databind: PolymorphicTypeValidator bypass via generic type parameters allows arbitrary class instantiation

CVE-2026-54513: jackson-databind: Array subtype allowlist bypass in BasicPolymorphicTypeValidator (allowIfSubTypeIsArray)

CVE-2026-54514: jackson-databind: InetSocketAddress deserialization triggers eager DNS resolution (SSRF)

This patched artifact is a drop-in replacement for com.fasterxml.jackson.core:jackson-databind 2.13.4.1 from Maven Central.

The general-purpose data-binding functionality and tree-model for Jackson Data Processor. It builds on core streaming parser/generator package, and uses Jackson Annotations for configuration.

Security Fix(es):

• jackson-databind: Jackson-databind: Security bypass allows arbitrary code execution (CVE-2026-54513)

• jackson-databind: jackson-databind: Arbitrary code execution via PolymorphicTypeValidator bypass (CVE-2026-54512)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

IdM PKI is an enterprise software system designed to manage enterprise Public Key Infrastructure deployments. IdM PKI consists of the following components:

• Certificate Authority (CA)
• Key Recovery Authority (KRA)
• Online Certificate Status Protocol (OCSP) Manager
• Token Key Service (TKS)
• Token Processing Service (TPS)
• Automatic Certificate Management Environment (ACME) Responder
• Enrollment over Secure Transport (EST) Responder

Security Fix(es):

• jackson-databind: Jackson-databind: Security bypass allows arbitrary code execution (CVE-2026-54513)

• jackson-databind: jackson-databind: Arbitrary code execution via PolymorphicTypeValidator bypass (CVE-2026-54512)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

jackson-databind contains the general-purpose data-binding functionality and tree-model for Jackson Data Processor. From 2.10.0 until 2.18.8, 2.21.4, and 3.1.4, 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 vulnerability is fixed in 2.18.8, 2.21.4, and 3.1.4.

The general-purpose data-binding functionality and tree-model for Jackson Data Processor. It builds on core streaming parser/generator package, and uses Jackson Annotations for configuration.

Security Fix(es):

• jackson-databind: Jackson-databind: Security bypass allows arbitrary code execution (CVE-2026-54513)
• jackson-databind: jackson-databind: Arbitrary code execution via PolymorphicTypeValidator bypass (CVE-2026-54512)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

IdM PKI is an enterprise software system designed to manage enterprise Public Key Infrastructure deployments. IdM PKI consists of the following components:

• Certificate Authority (CA)
• Key Recovery Authority (KRA)
• Online Certificate Status Protocol (OCSP) Manager
• Token Key Service (TKS)
• Token Processing Service (TPS)
• Automatic Certificate Management Environment (ACME) Responder
• Enrollment over Secure Transport (EST) Responder

Security Fix(es):

• jackson-databind: Jackson-databind: Security bypass allows arbitrary code execution (CVE-2026-54513)
• jackson-databind: jackson-databind: Arbitrary code execution via PolymorphicTypeValidator bypass (CVE-2026-54512)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

• CVE-2026-54512: fix PolymorphicTypeValidator bypass via unvalidated generic type parameters

• CVE-2026-54512: fix PolymorphicTypeValidator bypass via unvalidated generic type parameters

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 2 CVEs. Fixed in 2.14.2-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 5 CVEs. Fixed in 2.14.1-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 2 CVEs. Fixed in 2.17.3-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 9 CVEs. Fixed in 2.17.2-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 9 CVEs. Fixed in 2.11.1-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 6 CVEs. Fixed in 2.17.1-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 9 CVEs. Fixed in 2.13.4.2-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 9 CVEs. Fixed in 2.15.0-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 10 CVEs. Fixed in 2.13.4-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 9 CVEs. Fixed in 2.13.3-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 8 CVEs. Fixed in 2.10.5.1-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 7 CVEs. Fixed in 2.12.1-tuxcare.2.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 8 CVEs. Fixed in 2.18.5-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 11 CVEs. Fixed in 2.11.2-tuxcare.1.

TuxCare rebuilt com.fasterxml.jackson.core:jackson-databind to address 9 CVEs. Fixed in 2.13.5-tuxcare.1.