gam · filelock: StrictSoftFileLock and SoftReadWriteLock adopt a protocol directory another user created first, losing
Affects gamSource GCVE Database
Not known to be exploited · CVSS 6.3 Medium · fixed in 4.2.0 : update gam when convenient.
Data as of 9 Nov 2026, 20:05 UTC
Thin evidence
One scorer or none| CNA (GitHub_M) | CVSS 3.1 | 6.3 |
|---|
- Patch
- Available – fixed in 4.2.0
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:HExploitation 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
A fix is available in versions after 4.2.0 (not explicitly stated but implied by affected versions ending at 4.2.0). Users should upgrade to a fixed version once released. Until then, avoid using new lock paths in shared sticky directories where other local users can pre-create directories. Ensure that lock protocol directories are not pre-existing or owned by other users before acquiring locks. Monitor vendor advisories for official patches or updates. No generic mitigations such as disabling local user access apply specifically to this vulnerability.
Description
The vulnerability affects the StrictSoftFileLock and SoftReadWriteLock classes in the filelock library versions 3.30.0 through 4.2.0. These classes adopt a protocol directory created by another local user without verifying ownership, allowing that user to interfere with lock claims. This can lead to multiple writers entering critical sections simultaneously, silent compromise of lock integrity, and denial of service by causing lock acquisition to spin indefinitely or consume excessive memory. The issue requires the attacker to create the protocol directory before the lock user's first acquire, typically in shared sticky directories like /tmp. The vulnerability has no confidentiality impact but high integrity and availability impacts, with a CVSS 3.1 score of 6.3 (Medium).
References
- github.com/tox-dev/filelock/security/advisories/GHSA-9c4x-gm8v-wgc4 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-112911 (opens in a new tab)
- github.com/tox-dev/filelock/pull/839 (opens in a new tab)
- github.com/tox-dev/filelock/commit/bfa066d65a1ba9106f86ee9d027f7588b9c77e03 (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)