# jackson-databind has a PolymorphicTypeValidator bypass via generic type parameters that allows arbitrary class instantiation

Advisory record · `GHSA-j3rv-43j4-c7qm`

- **Identifiers:** `GHSA-j3rv-43j4-c7qm` · `CVE-2026-54512`
- **State:** Confirmed
- **Severity:** CVSS 8.1 High
- **Critical:** No
- **Weakness (CWE):** [CWE-184](https://cwe.mitre.org/data/definitions/184.html) · [CWE-502](https://cwe.mitre.org/data/definitions/502.html)
- **Tags:** [Insecure deserialization](https://agentprime.io/advisories/tag/deserialization.md) · [CWE-184](https://agentprime.io/advisories/tag/cwe-184.md)
- **Published:** 23 Jun 2026
- **Updated:** 28 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 23 Jun 2026, 21:21 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `com.fasterxml.jackson.core:jackson-databind` (Maven): affected `>=2.10.0, <2.18.8 || >=3.0.0, <3.1.4 || >=2.19.0, <2.21.4`; fixed in `2.18.8`, `3.1.4`, `2.21.4`
- `tools.jackson.core:jackson-databind` (Maven): affected `>=3.0.0, <3.1.4`; fixed in `3.1.4`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 8.1 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.011, the 64th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:16 UTC: First seen by agentprime
- 31 Oct 2026, 14:16 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-j3rv-43j4-c7qm)

## Sources

- [GitHub Advisory Database: GHSA-j3rv-43j4-c7qm](https://github.com/advisories/GHSA-j3rv-43j4-c7qm)
- [OSV: GHSA-j3rv-43j4-c7qm](https://osv.dev/vulnerability/GHSA-j3rv-43j4-c7qm)
- <https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-j3rv-43j4-c7qm>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-54512>
- <https://github.com/FasterXML/jackson-databind/issues/5988>
- <https://github.com/FasterXML/jackson-databind/commit/434d6c511de7fdd9872f29157aafb6162d12d8d5>
- <https://github.com/FasterXML/jackson-databind>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-j3rv-43j4-c7qm>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

---

The web page: <https://agentprime.io/advisories/GHSA-j3rv-43j4-c7qm/>. Everything for agents: <https://agentprime.io/llms.txt>.