CVE-2026-22701

Local file disruption via symlink creation race

Published Jan 10, 2026 · Updated Jan 10, 2026

A TOCTOU race in tox-dev filelock before 3.20.3 allows local users to disrupt SoftFileLock operations through a crafted symlink. SoftFileLock._acquire() checks path permissions before os.open() creates the lock, leaving a window in which a symlink can redirect the open. The attacker needs write access to the lock directory and must win the race, after which locking can fail, serialize resources incorrectly, or affect an unintended file.

CVSS severity5.3
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A TOCTOU race in tox-dev filelock before 3.20.3 allows local users to disrupt SoftFileLock operations through a crafted symlink. SoftFileLock._acquire() checks path permissions before os.open() creates the lock, leaving a window in which a symlink can redirect the open. The attacker needs write access to the lock directory and must win the race, after which locking can fail, serialize resources incorrectly, or affect an unintended file.

The record

CVE
CVE-2026-22701
Published
Jan 10, 2026
Updated
Jan 10, 2026
Vendor
tox-dev
Product
filelock
Classifications
CWE-362, CWE-367, CWE-59, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.20.3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

tox-dev · filelockversion=< 3.20.3

Published CVSS scores

5.3GitHub Advisory DatabaseCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
CWE-59Improper Link Resolution Before File Access ('Link Following')
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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