CVE-2026-54512
jackson-databind: PolymorphicTypeValidator bypass via generic type parameters allows arbitrary class instantiation
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High8.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Analyzed | 3.1 | High8.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 1.1% · top 35% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.1.
Weakness
Affected products
- affected >= 2.10.0, < 2.18.8
- affected >= 2.19.0, < 2.21.4
- affected >= 3.0.0, < 3.1.4
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Mavencom.fasterxml.jackson.core:jackson-databindGHSA-j3rv-43j4-c7qm (opens in a new tab)
- Maventools.jackson.core:jackson-databindGHSA-j3rv-43j4-c7qm (opens in a new tab)
References (3)
- https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-j3rv-43j4-c7qm (opens in a new tab)x_refsource_CONFIRMexploit
- https://github.com/FasterXML/jackson-databind/issues/5988 (opens in a new tab)x_refsource_MISC
- https://github.com/FasterXML/jackson-databind/commit/434d6c511de7fdd9872f29157aafb6162d12d8d5 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-j3rv-43j4-c7qm (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-54512)Record last updated .