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

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Summary

CVECVE-2026-54512
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-23 21:17:02 UTC
Updated2026-06-23 21:17:02 UTC
Descriptionjackson-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.

Risk And Classification

Primary CVSS: v3.1 8.1 HIGH from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Problem Types: CWE-184 | CWE-502 | CWE-184 CWE-184: Incomplete List of Disallowed Inputs | CWE-502 CWE-502: Deserialization of Untrusted Data

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.1HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.1HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA FasterXML Jackson-databind affected >= 2.10.0, < 2.18.8 Not specified
CNA FasterXML Jackson-databind affected >= 2.19.0, < 2.21.4 Not specified
CNA FasterXML Jackson-databind affected >= 3.0.0, < 3.1.4 Not specified

References

ReferenceSourceLinkTags
github.com/FasterXML/jackson-databind/issues/5988 [email protected] github.com
github.com/FasterXML/jackson-databind/commit/434d6c511de7fdd9872f29157aa... [email protected] github.com
github.com/FasterXML/jackson-databind/security/advisories/GHSA-j3rv-43j4... [email protected] github.com
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