# PolymorphicTypeValidator bypass via generic type arguments and array element types in jackson-databind allows arbitrary class instantiation (incomplete fix for CVE-2026-54512) \[CVE-2026-110879\]

Advisory record · `GHSA-m8xf-2cr7-77ph`

- **Identifiers:** `GHSA-m8xf-2cr7-77ph` · `CVE-2026-110879`
- **State:** Confirmed
- **Severity:** CVSS 9.8 Critical
- **Critical:** Yes: CVSS 9+
- **Weakness (CWE):** [CWE-502](https://cwe.mitre.org/data/definitions/502.html)
- **Tags:** [Insecure deserialization](https://agentprime.io/advisories/tag/deserialization.md)
- **Published:** 20 Oct 2026
- **Updated:** 20 Oct 2026
- **Reviewed by a person:** No

[Published by the maintainers](https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-m8xf-2cr7-77ph) · not yet reviewed by GitHub. The FasterXML/jackson-databind maintainers published this as a GitHub repository advisory; GitHub’s reviewed advisory replaces it here when it arrives.

Published by the FasterXML/jackson-databind maintainers at 20 Oct 2026, 22:44 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Critical

Critical, because:

- CVSS score 9.8: 9.0 or more.

How we decide what’s critical: <https://agentprime.io/advisories/critical.md>

## Affected packages

- `com.fasterxml.jackson.core:jackson-databind` (Maven): affected `>=2.10.0, <=2.18.11 || >=2.19.0, <=2.21.7 || >=2.22.0, <=2.22.3`; no fixed version yet
- `tools.jackson.core:jackson-databind` (Maven): affected `>=3.0.0, <=3.1.7 || >=3.2.0, <=3.2.3`; no fixed version yet

## 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

- 9.8 Critical, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`, from CNA (HeroDevs)

- **CISA KEV:** Not listed.
- **EPSS:** 0.012, the 68th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 20 Oct 2026, 22:44 UTC: [Published by the maintainers as a GitHub repository advisory](https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-m8xf-2cr7-77ph)
- 28 Oct 2026, 00:07 UTC: [Confirmed by the CVE List](https://www.cve.org/CVERecord?id=CVE-2026-110879)
- 28 Oct 2026, 01:16 UTC: [Confirmed by NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-110879)

## Sources

- [GitHub Advisory Database: GHSA-m8xf-2cr7-77ph](https://github.com/advisories/GHSA-m8xf-2cr7-77ph)
- [OSV: GHSA-m8xf-2cr7-77ph](https://osv.dev/vulnerability/GHSA-m8xf-2cr7-77ph)
- <https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-m8xf-2cr7-77ph>

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-m8xf-2cr7-77ph>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-m8xf-2cr7-77ph/>. Everything for agents: <https://agentprime.io/llms.txt>.