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Amazon Linux 2023 : python3.13-filelock (ALAS2023-2026-1411)

medium Nessus Plugin ID 299516

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Synopsis

The remote Amazon Linux 2023 host is missing a security update.

Description

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1411 advisory.

 filelock is a platform-independent file lock for Python. In versions prior to 3.20.1, a Time-of-Check- Time-of-Use (TOCTOU) race condition allows local attackers to corrupt or truncate arbitrary user files through symlink attacks. The vulnerability exists in both Unix and Windows lock file creation where filelock checks if a file exists before opening it with O_TRUNC. An attacker can create a symlink pointing to a victim file in the time gap between the check and open, causing os.open() to follow the symlink and truncate the target file. All users of filelock on Unix, Linux, macOS, and Windows systems are impacted.
 The vulnerability cascades to dependent libraries. The attack requires local filesystem access and ability to create symlinks (standard user permissions on Unix; Developer Mode on Windows 10+). Exploitation succeeds within 1-3 attempts when lock file paths are predictable. The issue is fixed in version 3.20.1.
 If immediate upgrade is not possible, use SoftFileLock instead of UnixFileLock/WindowsFileLock (note:
 different locking semantics, may not be suitable for all use cases); ensure lock file directories have restrictive permissions (chmod 0700) to prevent untrusted users from creating symlinks; and/or monitor lock file directories for suspicious symlinks before running trusted applications. These workarounds provide only partial mitigation. The race condition remains exploitable. Upgrading to version 3.20.1 is strongly recommended. (CVE-2025-68146)

 filelock is a platform-independent file lock for Python. Prior to version 3.20.3, a TOCTOU race condition vulnerability exists in the SoftFileLock implementation of the filelock package. An attacker with local filesystem access and permission to create symlinks can exploit a race condition between the permission validation and file creation to cause lock operations to fail or behave unexpectedly. The vulnerability occurs in the _acquire() method between raise_on_not_writable_file() (permission check) and os.open() (file creation). During this race window, an attacker can create a symlink at the lock file path, potentially causing the lock to operate on an unintended target file or leading to denial of service. This issue has been patched in version 3.20.3. (CVE-2026-22701)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Run 'dnf update python3.13-filelock --releasever 2023.10.20260216' or or 'dnf update --advisory ALAS2023-2026-1411 --releasever 2023.10.20260216' to update your system.

See Also

https://alas.aws.amazon.com//AL2023/ALAS2023-2026-1411.html

https://alas.aws.amazon.com/faqs.html

https://explore.alas.aws.amazon.com/CVE-2025-68146.html

https://explore.alas.aws.amazon.com/CVE-2026-22701.html

Plugin Details

Severity: Medium

ID: 299516

File Name: al2023_ALAS2023-2026-1411.nasl

Version: 1.2

Type: Local

Agent: unix

Published: 2/19/2026

Updated: 3/16/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.3

CVSS v2

Risk Factor: Medium

Base Score: 5.7

Temporal Score: 4.5

Vector: CVSS2#AV:L/AC:H/Au:S/C:P/I:C/A:C

CVSS Score Source: CVE-2025-68146

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.9

Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:amazon:linux:2023, p-cpe:/a:amazon:linux:python3.13-filelock

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 2/18/2026

Vulnerability Publication Date: 12/16/2025

Reference Information

CVE: CVE-2025-68146, CVE-2026-22701