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    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

    Published:May 30, 2025
    Last Modified:Apr 20, 2026
    EPS:May 30, 2025
    EPSS Score:0.00041
    CVSS Score:5.9

    Affected Products

    Vendor
    Perl
    Product
    Perl

    Exploits

    No exploit reference

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    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
    http://www.openwall.com/lists/oss-security/2025/05/23/1
    http://www.openwall.com/lists/oss-security/2025/05/30/4
    http://www.openwall.com/lists/oss-security/2025/06/02/2
    http://www.openwall.com/lists/oss-security/2025/06/02/5
    http://www.openwall.com/lists/oss-security/2025/06/02/6
    http://www.openwall.com/lists/oss-security/2025/06/02/7
    http://www.openwall.com/lists/oss-security/2025/06/03/1
    https://lists.debian.org/debian-lts-announce/2026/04/msg00018.html

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High