CVE-2025-68146Public exploit

Arbitrary file truncation via lock-path symlink race

Published Dec 16, 2025 · Updated Dec 16, 2025

TOCTOU race in tox-dev filelock before 3.20.1 allows local users to truncate arbitrary files through crafted lock-path symlinks. UnixFileLock checks existence before os.open uses O_TRUNC, while WindowsFileLock opens after a non-atomic writability check; both follow a substituted link. Exploitation requires local filesystem access, a predictable lock path, and symlink creation rights, allowing files writable by the victim process to be reduced to zero bytes.

CVSS severity6.3
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TOCTOU race in tox-dev filelock before 3.20.1 allows local users to truncate arbitrary files through crafted lock-path symlinks. UnixFileLock checks existence before os.open uses O_TRUNC, while WindowsFileLock opens after a non-atomic writability check; both follow a substituted link. Exploitation requires local filesystem access, a predictable lock path, and symlink creation rights, allowing files writable by the victim process to be reduced to zero bytes.

The record

CVE
CVE-2025-68146
Published
Dec 16, 2025
Updated
Dec 16, 2025
Vendor
tox-dev
Product
filelock
Classifications
CWE-59, CWE-362, CWE-367, T1485
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Dec 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 16, 2025Record 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=< 3.20.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

tox-dev · filelockversion=< 3.20.1

Published CVSS scores

6.3GitHub, Inc.CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
6.5NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-59Improper Link Resolution Before File Access ('Link Following')
CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
T1485Data Destruction

Public exploit references

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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