# jackson-databind: Comparable missing from DefaultBaseTypeLimitingValidator's unsafe base types (incomplete PolymorphicTypeValidator denylist)

Advisory record · `GHSA-gx83-3vf8-gh7j`

- **Identifiers:** `GHSA-gx83-3vf8-gh7j` · `CVE-2026-83557`
- **State:** Confirmed
- **Severity:** CVSS 5.6 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-502](https://cwe.mitre.org/data/definitions/502.html) · [CWE-915](https://cwe.mitre.org/data/definitions/915.html)
- **Tags:** [Insecure deserialization](https://agentprime.io/advisories/tag/deserialization.md) · [Broken access control](https://agentprime.io/advisories/tag/access-control.md)
- **Published:** 28 Sept 2026
- **Updated:** 28 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 28 Sept 2026, 20:44 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `tools.jackson.core:jackson-databind` (Maven): affected `>=3.0.0, <3.1.6 || >=3.2.0, <3.2.2`; fixed in `3.1.6`, `3.2.2`
- `com.fasterxml.jackson.core:jackson-databind` (Maven): affected `>=2.11.0, <2.18.10 || >=2.19.0, <2.21.6 || >=2.22.0, <2.22.2`; fixed in `2.18.10`, `2.21.6`, `2.22.2`

## 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

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.0072, the 53rd 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-gx83-3vf8-gh7j)

## Sources

- [GitHub Advisory Database: GHSA-gx83-3vf8-gh7j](https://github.com/advisories/GHSA-gx83-3vf8-gh7j)
- [OSV: GHSA-gx83-3vf8-gh7j](https://osv.dev/vulnerability/GHSA-gx83-3vf8-gh7j)
- <https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-gx83-3vf8-gh7j>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-83557>
- <https://github.com/FasterXML/jackson-databind/issues/6156>
- <https://github.com/FasterXML/jackson-databind/pull/6155>
- <https://github.com/FasterXML/jackson-databind/commit/eb3b7fc0f9c0d27f471550ac3316b17d1987388f>
- <https://github.com/FasterXML/jackson-databind>
- <https://github.com/FasterXML/jackson-databind/releases/tag/jackson-databind-2.18.10>
- <https://github.com/FasterXML/jackson-databind/releases/tag/jackson-databind-2.21.6>
- <https://github.com/FasterXML/jackson-databind/releases/tag/jackson-databind-2.22.2>
- <https://github.com/FasterXML/jackson-databind/releases/tag/jackson-databind-3.1.6>
- <https://github.com/FasterXML/jackson-databind/releases/tag/jackson-databind-3.2.2>

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-gx83-3vf8-gh7j>, 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-gx83-3vf8-gh7j/>. Everything for agents: <https://agentprime.io/llms.txt>.