# OpenC3 COSMOS allows arbitrary writes to plugins directory via path-traversed config filenames

Advisory record · `GHSA-4jvx-93h3-f45h`

- **Identifiers:** `GHSA-4jvx-93h3-f45h` · `CVE-2026-42085` · `PYSEC-2026-2243`
- **State:** Confirmed
- **Severity:** CVSS 4.3 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-23](https://cwe.mitre.org/data/definitions/23.html)
- **Tags:** [Path traversal](https://agentprime.io/advisories/tag/path-traversal.md)
- **Published:** 22 Apr 2026
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 22 Apr 2026, 22:22 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `openc3` (RubyGems): affected `<6.10.5 || >=7.0.0.pre.rc1, <7.0.0-rc3`; fixed in `6.10.5`, `7.0.0-rc3`

## 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

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.0031, the 24th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 15:04 UTC: First seen by agentprime
- 31 Oct 2026, 15:04 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/PYSEC-2026-2243)

## Sources

- [GitHub Advisory Database: GHSA-4jvx-93h3-f45h](https://github.com/advisories/GHSA-4jvx-93h3-f45h)
- [OSV: GHSA-4jvx-93h3-f45h](https://osv.dev/vulnerability/GHSA-4jvx-93h3-f45h)
- <https://github.com/OpenC3/cosmos/security/advisories/GHSA-4jvx-93h3-f45h>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-42085>
- <https://github.com/OpenC3/cosmos/commit/9957a9fa460c0c0cf5cdbf6a5931bbdd025246a5>
- <https://github.com/OpenC3/cosmos/commit/e6efccbd148ba0e3361c5891027f2373aa140d42>
- <https://github.com/OpenC3/cosmos>
- <https://github.com/OpenC3/cosmos/releases/tag/v6.10.5>
- <https://github.com/OpenC3/cosmos/releases/tag/v7.0.0-rc3>
- <https://github.com/rubysec/ruby-advisory-db/blob/master/gems/openc3/CVE-2026-42085.yml>

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-4jvx-93h3-f45h>, 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-4jvx-93h3-f45h/>. Everything for agents: <https://agentprime.io/llms.txt>.