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Vulnerabilities

Security fix · CVE-2026-112935

filelock is a platform-independent file lock for Python.

Published Oct 20, 2026 · catalog updated Oct 21, 2026 · filelock is a platform-independent

Last checked Nov 3, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-112935. EPSS is 0.13%. Act only if a listed version of filelock is a platform-independent is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (filelock is a platform-independent).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium4.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.13%
Remediation
Version ranges on file
Affected products
cpe tox-dev/filelock · pypi filelock

filelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can break a stale marker after an attacker frees its own marker following the stale read, an honest contender creates a live successor on the reused inode, and the successor's modification time is not newer than the saved observation, causing the live marker to be removed and two holders to be admitted. This issue is fixed in version 4.2.1.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe tox-dev/filelock< 4.2.1
  • pypi filelockversion unspecified

How to fix CVE-2026-112935

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-112935. EPSS is 0.13%. Act only if a listed version of filelock is a platform-independent is installed.

Which versions are affected?

Compare what you have installed with < 4.2.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition. EPSS 0.13%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 20, 2026 · NIST NVD

    Detected

    filelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can break a stale marker after an attacker frees its own marker following the stale read, an honest contender creates a live successor on the reused inode, and the successor's modification time is not newer than the saved observation, causing the live marker to be removed and two holders to be admitted.

  2. Oct 20, 2026 · NIST NVD

    Updated

    filelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can break a stale marker after an attacker frees its own marker following the stale read, an honest contender creates a live successor on the reused inode, and the successor's modification time is not newer than the saved observation, causing the live marker to be removed and two holders to be admitted.

  3. Oct 21, 2026 · NIST NVD

    Updated

    filelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can break a stale marker after an attacker frees its own marker following the stale read, an honest contender creates a live successor on the reused inode, and the successor's modification time is not newer than the saved observation, causing the live marker to be removed and two holders to be admitted.

Sources

  • CVE.orgVulnerability recordCVE-2026-112935

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-112935

    30-day exploitation probability 0.13%

    first.org
  • GitLab Advisory DatabasePackage advisoryCVE-2026-112935

    The stale-lock break shared by SoftFileLock, MarkerSoftFileLock and SoftFileLease (and their async variants, and a FileLock that has fallen back to a soft lock on ENOSYS, the "not implemented" error) recognises the marker it judged stale by two values. The marker is the lock file at , whose presence says a process holds the lock. The values are its inode number (the kernel's identity for a file, i

    advisories.gitlab.com
  • NIST NVDVulnerability recordCVE-2026-112935

    filelock is a platform-independent file lock for Python. From 3.22.0 until 4.2.1, SoftFileLock can break a stale marker after an attacker frees its own marker following the stale read, an honest contender creates a live successor on the reused inode, and the successor's modificat

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 3, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 3, 2026
  • GitLab Advisory DatabaseOct 30, 2026
  • NIST NVDOct 22, 2026
  • CVE.orgOct 21, 2026