CVE-2025-40909: medium-severity vulnerability in perl
Perl threads have a working directory race condition where file operations may target unintended paths
Published · Updated
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.9epss 0.5%
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
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Affected products
perl · perlRelated CVEs — perl
In the same product, most dangerous first.
References
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1098226http://seclists.org/fulldisclosure/2025/Sep/53http://seclists.org/fulldisclosure/2025/Sep/54http://seclists.org/fulldisclosure/2025/Sep/55https://github.com/Perl/perl5/commit/11a11ecf4bea72b17d250cfb43c897be1341861ehttps://github.com/Perl/perl5/commit/918bfff86ca8d6d4e4ec5b30994451e0bd74aba9.patchhttps://github.com/Perl/perl5/issues/10387https://github.com/Perl/perl5/issues/23010https://lists.debian.org/debian-lts-announce/2026/04/msg00018.htmlhttps://perldoc.perl.org/5.14.0/perl5136delta#Directory-handles-not-copied-to-threadshttps://www.openwall.com/lists/oss-security/2025/05/22/2http://www.openwall.com/lists/oss-security/2025/05/23/1