CVE-2025-40909 (CVSS 5.9)

Description

Perl threads have a working directory race condition where file operations may target unintended paths. If a directory handle is open at thread creation, the process-wide current working directory is temporarily changed in order to clone that handle for the new thread, which is visible from any third (or more) thread already running. This may lead to unintended operations such as loading code or accessing files from unexpected locations, which a local attacker may be able to exploit. The bug was introduced in commit 11a11ecf4bea72b17d250cfb43c897be1341861e and released in Perl version 5.13.6

Is your site exposed to CVE-2025-40909?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

5.9

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Weakness Type (CWE)

CWE-426 CWE-426

CWE-689 CWE-689

References

Other References

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1098226 https://github.com/Perl/perl5/commit/11a11ecf4bea72b17d250cfb43c897be1341861e https://github.com/Perl/perl5/commit/918bfff86ca8d6d4e4ec5b30994451e0bd74aba9.patch https://github.com/Perl/perl5/issues/10387 https://github.com/Perl/perl5/issues/23010 https://perldoc.perl.org/5.14.0/perl5136delta#Directory-handles-not-copied-to-threads https://www.openwall.com/lists/oss-security/2025/05/22/2 http://seclists.org/fulldisclosure/2025/Sep/53 http://seclists.org/fulldisclosure/2025/Sep/54 http://seclists.org/fulldisclosure/2025/Sep/55

Frequently Asked Questions

What is CVE-2025-40909? +

Perl threads have a working directory race condition where file operations may target unintended paths. If a directory handle is open at thread creation, the process-wide current working directory is temporarily changed in order to clone that handle for the new thread, which is visible from any third (or more) thread already running. This may lead to unintended operations such as loading code or accessing files from unexpected locations, which a local attacker may be able to exploit. The bug was introduced in commit 11a11ecf4bea72b17d250cfb43c897be1341861e and released in Perl version 5.13.6 It has a CVSS v3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2025-40909? +

CVE-2025-40909 has a CVSS v3.1 score of 5.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2025-40909? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2024-3220

There is a defect in the CPython standard library module “mimetypes” where on Windows the default list of known file …

CVE-2025-26624

Rufus is a utility that helps format and create bootable USB flash drives. A DLL hijacking vulnerability in Rufus 4.6.2208 …

CVE-2025-4971

Broadcom Automic Automation Agent Unix versions < 24.3.0 HF4 and < 21.0.13 HF1 allow low privileged users who have execution …

CVE-2025-0141

An incorrect privilege assignment vulnerability in the Palo Alto Networks GlobalProtect™ App on enables a locally authenticated non administrative user …

CVE-2025-9267

In Seagate Toolkit on Windows a vulnerability exists in the Toolkit Installer prior to versions 2.35.0.6 where it attempts to …

CVE-2023-32266

Untrusted Search Path vulnerability in OpenText™ Application Lifecycle Management (ALM),Quality Center allows Code Inclusion. The vulnerability allows a user to …

CVE-2025-40909