CVE-2026-112937 — filelock: ReadWriteLock on the hard-link route deletes any directory another user renames onto its .filelock-* link directory name
filelock is a platform-independent file lock for Python. From 4.1.0 until 4.2.1, ReadWriteLock can remove a randomized .filelock-* private-hard-link directory during cleanup, allowing another local user with rename access in a non-sticky parent to observe a live name or forge a dead-owner sweep name and rename a sibling directory onto it for deletion. This issue is fixed in version 4.2.1.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Tox-dev Filelock).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (logic error), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 6.1 | CVSS 3.1 | Medium | 1.8 | 4.2 | security-advisories@github.com via NIST National Vulnerability Database |
| 6.1 | CVSS 3.1 | Medium | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L (score shown at the top: security-advisories@github.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
Timeline
What happened to this CVE, newest first.
- 2026
- Source status changed · Received → Undergoing Analysis
- Affected products added · tox-dev/filelock
- Record published
- CVSS changed · 6.1
- Source status changed · → Received
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× References added · Oct 20, 2026 – Oct 20, 2026
- 1× Official description updated · Oct 20, 2026 – Oct 20, 2026
References
4 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-112939 filelock: SoftFileLock removes a live holder's marker when another user forges the PID in a writable marker 23h
- Medium CVE-2026-112934 filelock: SoftReadWriteLock holder refresh writes through a hard link and hangs on a named pipe that another local user renames over its record 23h
- Medium CVE-2026-112935 filelock: SoftFileLock stale-lock break removes a live lock file on a reused inode number and admits two holders 23h
- Medium CVE-2026-112936 filelock: ReadWriteLock follows a symlink at the lock path into SQLite 23h
- Low CVE-2026-112941 filelock: SoftReadWriteLock follows a lock tree swapped in after its first acquire and writes lock records into directories of the user running the lock 23h
- High CVE-2026-112940 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 23h
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No FIRST EPSS score.
- No fixed version, patch or mitigation documented.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-112937 is "filelock: ReadWriteLock on the hard-link route deletes any directory another user renames onto its .filelock-* link directory name", rated Medium. It affects Filelock (Tox-dev); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.1 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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