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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-54513: 1.23% estimated exploitation activity in the next 30 days; percentile 68.86 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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, <…

Published by the source

23 Jun 2026, 21:22 UTC

Last modified by the source

11 Sep 2026, 15:33 UTC

Source last checked

26 Oct 2026, 16:55 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-rmj7-2vxq-3g9f

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# Patch Next advisory brief: CVE-2026-54513

Advisory: jackson-databind has an array subtype allowlist bypass in BasicPolymorphicTypeValidator (allowIfSubTypeIsArray)
IDs: CVE-2026-54513, GHSA-rmj7-2vxq-3g9f
Record: https://patchnext.com/advisories/cve-2026-54513 (revision 1, source checked 26 Oct 2026, 16:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: tools.jackson.core:jackson-databind 3.1.4; com.fasterxml.jackson.core:jackson-databind 3.1.4, 2.21.4, 2.18.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven tools.jackson.core:jackson-databind: affected >= 3.0.0, < 3.1.4; fixed in 3.1.4
- Maven com.fasterxml.jackson.core:jackson-databind: affected >= 2.10.0, < 2.18.8; >= 2.19.0, < 2.21.4; >= 3.0.0, < 3.1.4; fixed in 2.21.4, 2.18.8, 3.1.4

## Suggested inspection (read-only)
- Maven tools.jackson.core:jackson-databind: check the installed version with your package manager.
- Maven com.fasterxml.jackson.core:jackson-databind: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on tools.jackson.core:jackson-databind, com.fasterxml.jackson.core:jackson-databind.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-rmj7-2vxq-3g9f (GitHub-reviewed advisory GHSA-rmj7-2vxq-3g9f lists affected ranges: Maven com.fasterxml.jackson.core:jackson-databind >=2.10.0 =2.19.0 =3.0.0 =3.0.0 <3.1.4)

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