# FoundationAgents MetaGPT: Deserialization through flawed argument mapping via Message.check_instruct_content()

Advisory record · `GHSA-3c3g-7hwg-9qmr`

- **Identifiers:** `GHSA-3c3g-7hwg-9qmr` · `CVE-2026-10566` · `PYSEC-2026-2637`
- **State:** Confirmed
- **Severity:** CVSS 4.8 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-20](https://cwe.mitre.org/data/definitions/20.html) · [CWE-502](https://cwe.mitre.org/data/definitions/502.html)
- **Tags:** [Insecure deserialization](https://agentprime.io/advisories/tag/deserialization.md) · [CWE-20](https://agentprime.io/advisories/tag/cwe-20.md)
- **Published:** 2 Jun 2026
- **Updated:** 13 Jul 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 2 Jun 2026, 03:31 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `metagpt` (PyPI): affected `<=0.8.2`; 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

- 4.8 Medium, CVSS 4.0: `CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`, from CNA (VulDB)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0012, the 1st percentile, on 10 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:59 UTC: First seen by agentprime
- 31 Oct 2026, 14:59 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-3c3g-7hwg-9qmr)

## Sources

- [GitHub Advisory Database: GHSA-3c3g-7hwg-9qmr](https://github.com/advisories/GHSA-3c3g-7hwg-9qmr)
- [OSV: GHSA-3c3g-7hwg-9qmr](https://osv.dev/vulnerability/GHSA-3c3g-7hwg-9qmr)
- <https://nvd.nist.gov/vuln/detail/CVE-2026-10566>
- <https://github.com/FoundationAgents/MetaGPT/issues/2038>
- <https://github.com/FoundationAgents/MetaGPT>
- <https://vuldb.com/cve/CVE-2026-10566>
- <https://vuldb.com/submit/828301>
- <https://vuldb.com/vuln/367673>
- <https://vuldb.com/vuln/367673/cti>

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-3c3g-7hwg-9qmr>, 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-3c3g-7hwg-9qmr/>. Everything for agents: <https://agentprime.io/llms.txt>.