# filelock: SoftFileLock stale-break restore follows a swapped-in symbolic link and hard-links a file of the user running the lock into the lock directory Advisory record · `GHSA-crv4-6mhj-j5jh` - **Identifiers:** `GHSA-crv4-6mhj-j5jh` · `CVE-2026-112914` - **State:** Confirmed - **Severity:** CVSS 5.3 Medium - **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, 22:00 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. ## Affected packages - `filelock` (PyPI): affected `>=4.1.0, <4.2.1`; fixed in `4.2.1` ## Machine-written summary Summary written by Claude Haiku from the source advisory. Not reviewed by a person. > Versions 4.1.0 through 4.2.0 of the filelock Python package (PyPI) are affected, and version 4.2.1 fixes this. In the soft-lock stale-break restore path, a local user who can write a shared lock directory without the sticky bit can swap in a symbolic link so that the lock user's process hard-links one of its own files into that directory. The other user can then read the file's size, times, mode and owner, and can rename the new name; on 4.2.0 a later lock truncated the file. Upgrade to filelock 4.2.1 or later. Written 1 Nov 2026. ## 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 - 5.3 Medium, CVSS 3.1: `CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N`, from CNA (GitHub_M) - **CISA KEV:** Not listed. - **EPSS:** 0.0016, the 5th 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-crv4-6mhj-j5jh) ## Sources - [GitHub Advisory Database: GHSA-crv4-6mhj-j5jh](https://github.com/advisories/GHSA-crv4-6mhj-j5jh) - [OSV: GHSA-crv4-6mhj-j5jh](https://osv.dev/vulnerability/GHSA-crv4-6mhj-j5jh) - - - - - - 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 (), 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: - In a browser: reads your lockfile in the browser, never uploading it. - Whether it touches your code, with file and line: the Claude Code plugin, - As JSON: , or `POST https://api.agentprime.io/v1/match` with your packages () --- The web page: . Everything for agents: .