gam · filelock: SoftFileLock stale-lock break removes a live lock file on a reused inode number and admits two holders
Affects gamSource GCVE Database
Not known to be exploited · CVSS 4.7 Medium.
Data as of 9 Nov 2026, 20:04 UTC
Thin evidence
One scorer or none| CNA (GitHub_M) | CVSS 3.1 | 4.7 |
|---|
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 20 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Homebrewgampkg:brew/gamOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Users should upgrade to a version of filelock later than 4.2.0 once available, as the vulnerability affects versions >=3.22.0 and <=4.2.0. Until a fixed version is released, avoid using filelock on filesystems that immediately reuse inode numbers (such as ext4 or xfs) in directories writable by unprivileged users with sticky bits (e.g., /tmp). Alternatively, use StrictSoftFileLock which is not affected by this issue. Restrict write permissions on lock directories to trusted users only to prevent local attackers from creating files there. Monitor vendor advisories for official patches or updates.
Description
A vulnerability in the filelock library versions 3.22.0 through 4.2.0 allows a local unprivileged user to cause two processes of the lock owner to simultaneously hold the same soft file lock. This occurs due to a race condition in the stale-lock break mechanism that relies on inode numbers and modification times, which can be manipulated on filesystems like ext4 and xfs that reuse inode numbers immediately. The issue requires a sticky shared directory writable by the attacker and at least two contending processes by the lock owner. The vulnerability impacts integrity by allowing concurrent lock holders without detection but does not affect confidentiality or availability.
References
- github.com/tox-dev/filelock/security/advisories/GHSA-fq56-3cx3-fjxp (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-112935 (opens in a new tab)
- github.com/tox-dev/filelock/pull/843 (opens in a new tab)
- github.com/tox-dev/filelock/commit/740ff666b62a88496c8d7394e4e6230605e4d62b (opens in a new tab)
- github.com/tox-dev/filelock (opens in a new tab)
- github.com/tox-dev/filelock/releases/tag/4.2.1 (opens in a new tab)