A crafted regular expression when compiled by perl 5.30.0 through 5.38.0 can cause a one attacker controlled byte buffer overflow in a heap allocated buffer

• https://perldoc.perl.org/perl5342delta
• https://perldoc.perl.org/perl5363delta
• https://perldoc.perl.org/perl5381delta
• https://perldoc.perl.org/perl5382delta
• https://perldoc.perl.org/perl5400delta

A heap buffer overflow vulnerability was discovered in Perl. Release branches 5.34, 5.36, 5.38 and 5.40 are affected, including development versions from 5.33.1 through 5.41.10. When there are non-ASCII bytes in the left-hand-side of the `tr` operator, `S_do_trans_invmap` can overflow the destination pointer `d`.    $ perl -e '$_ = "\x{FF}" x 1000000; tr/\xFF/\x{100}/;'    Segmentation fault (core dumped) It is believed that this vulnerability can enable Denial of Service and possibly Code Execution attacks on platforms that lack sufficient defenses.

• https://github.com/Perl/perl5/commit/87f42aa0e0096e9a346c9672aa3a0bd3bef8c1dd.patch
• https://metacpan.org/release/SHAY/perl-5.38.4/changes
• https://metacpan.org/release/SHAY/perl-5.40.2/changes

Perl for Windows relies on the system path environment variable to find the shell (cmd.exe). When running an executable which uses Windows Perl interpreter, Perl attempts to find and execute cmd.exe within the operating system. However, due to path search order issues, Perl initially looks for cmd.exe in the current working directory. An attacker with limited privileges can exploit this behavior by placing cmd.exe in locations with weak permissions, such as C:\ProgramData. By doing so, when an administrator attempts to use this executable from these compromised locations, arbitrary code can be executed.

• https://github.com/ycdxsb/WindowsPrivilegeEscalation
• https://perldoc.perl.org/perl5342delta
• https://perldoc.perl.org/perl5363delta
• https://perldoc.perl.org/perl5381delta
• https://perldoc.perl.org/perl5382delta
• https://perldoc.perl.org/perl5400delta

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

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

In Perl before 5.38.2, S_parse_uniprop_string in regcomp.c can write to unallocated space because a property name associated with a \p{...} regular expression construct is mishandled. The earliest affected version is 5.30.0.

• https://github.com/Perl/perl5/commit/ff1f9f59360afeebd6f75ca1502f5c3ebf077da3
• https://github.com/Perl/perl5/commit/12c313ce49b36160a7ca2e9b07ad5bd92ee4a010
• https://github.com/Perl/perl5/commit/7047915eef37fccd93e7cd985c29fe6be54650b6