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

> CVE-2026-54512: jackson-databind: PolymorphicTypeValidator bypass via generic type parameters allows arbitrary class instantiation. CVSS 8.1 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-54512
Last updated: 2026-06-27T21:01:36Z

- Published: 2026-06-23 20:56 UTC · Updated: 2026-06-27 21:01 UTC · Assigner: GitHub\_M
- CVSS: 8.1 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS: 0.94%, 61th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-184, CWE-502

## 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.

## Affected vendors and products

- FasterXML: jackson-databind

## Tracked companies

- [Confluence](https://rewindex.com/company/confluence.md)
- [Jira](https://rewindex.com/company/jira.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-54512)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-54512)
- [https://github.com/FasterXML/jackson-databind/commit/434d6c511de7fdd9872f29157aafb6162d12d8d5](https://github.com/FasterXML/jackson-databind/commit/434d6c511de7fdd9872f29157aafb6162d12d8d5)
- [https://github.com/FasterXML/jackson-databind/issues/5988](https://github.com/FasterXML/jackson-databind/issues/5988)
- [https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-j3rv-43j4-c7qm](https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-j3rv-43j4-c7qm)

---

_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


---
Canonical: https://rewindex.com/cve/CVE-2026-54512 · Markdown: https://rewindex.com/cve/CVE-2026-54512.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-54512 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:13:40.891Z