CVE-2026-112906: filelock is a platform-independent file lock for Python

Q: How do I fix CVE-2026-112906?

filelock: upgrade to 4.2.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-112906 being exploited?

CVE-2026-112906 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-112906 affect?

CVE-2026-112906 affects filelock. Severity is medium (CVSS 4.7). filelock is a platform-independent file lock for Python. From 4.1.0 until 4.2.1, SoftFileLock versions from 4.1.0 can reuse a stale observation when an attacker pre-dates and removes its own marker, at least two lock-user processes are wait

Q: How urgent is CVE-2026-112906?

Priority 24/100. Public exploit reference

Routine

MEDIUM 4.7UPGRADE

CVE-2026-112906 is a medium-severity flaw (CVSS 4.7) affecting filelock. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

filelock is a platform-independent file lock for Python. From 4.1.0 until 4.2.1, SoftFileLock versions from 4.1.0 can reuse a stale observation when an attacker pre-dates and removes its own marker, at least two lock-user processes are waiting, coarse or matching modification times preserve the observation, and an honest contender creates a fresh marker on the reused inode, causing that live marker to be removed as stale. This issue is fixed in v

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	4.7 (Medium)
Attack vector	Local
Attack complexity	High
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 90%)
CISA exploited list	No
Weakness	CWE-694, CWE-362
Published	2026-10-20
Last modified	2026-10-27

Publisher (CNA): GitHub, Inc. · Vendor: tox-dev

Last updated 2026-10-27 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-10-20 15:17 UTCPublished CVE record published
2026-10-27 21:06 UTCUpdated Record last modified

tox-dev filelock UPGRADE

Affected: >= 4.1.0 and < 4.2.1

Fixed in: 4.2.1

Safe to downgrade to: a release before 4.1.0

1. Check installed version

pip show filelock

2. UPGRADE to 4.2.1

pip install --upgrade "filelock>=4.2.1"

3. If no update is available yet, DOWNGRADE to a release before 4.1.0

pip index versions filelock pip install "filelock<4.1.0"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-112906?

filelock: upgrade to 4.2.1. Exact commands for each OS are on this page.

Is CVE-2026-112906 being exploited?

CVE-2026-112906 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-112906 affect?

CVE-2026-112906 affects filelock. Severity is medium (CVSS 4.7). filelock is a platform-independent file lock for Python. From 4.1.0 until 4.2.1, SoftFileLock versions from 4.1.0 can reuse a stale observation when an attacker pre-dates and removes its own marker, at least two lock-user processes are wait

How urgent is CVE-2026-112906?

Priority 24/100. Public exploit reference

Software pages

Python vulnerabilities

Related CVEs

CVE-2026-112909 MEDIUM 6.1 UPGRADE filelock is a platform-independent file lock for Python
CVE-2026-112940 HIGH 7.1 UPGRADE filelock is a platform-independent file lock for Python
CVE-2026-112934 MEDIUM 6.1 UPGRADE filelock is a platform-independent file lock for Python
CVE-2026-112911 MEDIUM 6.3 UPGRADE filelock is a platform-independent file lock for Python
CVE-2026-112912 LOW 2.5 UPGRADE filelock is a platform-independent file lock for Python

References

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