# filelock ReadWriteLock: SQLite reopens the lock database by name, so a planted symlink or journal file makes the lock user's process overwrite or unlink its own files

Advisory record · `GHSA-v4x8-3wr5-3wq8`

- **Identifiers:** `GHSA-v4x8-3wr5-3wq8` · `CVE-2026-112940`
- **State:** Confirmed
- **Severity:** CVSS 7.1 High
- **Critical:** No
- **Weakness (CWE):** [CWE-59](https://cwe.mitre.org/data/definitions/59.html) · [CWE-363](https://cwe.mitre.org/data/definitions/363.html)
- **Tags:** [Path traversal](https://agentprime.io/advisories/tag/path-traversal.md) · [CWE-363](https://agentprime.io/advisories/tag/cwe-363.md)
- **Published:** 23 Oct 2026
- **Updated:** 23 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 23 Oct 2026, 21:59 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `filelock` (PyPI): affected `>=3.20.4, <4.2.1`; fixed in `4.2.1`

## 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

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.0019, the 8th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:07 UTC: First seen by agentprime
- 31 Oct 2026, 14:07 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-v4x8-3wr5-3wq8)

## Sources

- [GitHub Advisory Database: GHSA-v4x8-3wr5-3wq8](https://github.com/advisories/GHSA-v4x8-3wr5-3wq8)
- [OSV: GHSA-v4x8-3wr5-3wq8](https://osv.dev/vulnerability/GHSA-v4x8-3wr5-3wq8)
- <https://github.com/tox-dev/filelock/security/advisories/GHSA-v4x8-3wr5-3wq8>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-112940>
- <https://github.com/tox-dev/filelock/pull/834>
- <https://github.com/tox-dev/filelock/commit/5e3f2ec0c5fb17cb2635b60b2b68bc63ab81ca2d>
- <https://github.com/tox-dev/filelock>
- <https://github.com/tox-dev/filelock/releases/tag/4.2.1>

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-v4x8-3wr5-3wq8>, 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-v4x8-3wr5-3wq8/>. Everything for agents: <https://agentprime.io/llms.txt>.