oss-security - CVE-2026-8376: Perl versions through 5.43.10 have a heap buffer overflow when compiling regular expressions with a repeated fixed string on 32-bit builds

Follow @Openwall on Twitter for new release announcements and other news

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <ba11f0276bd2dd692251a779a35d2e84@cpansec.org>
Date: Mon, 25 May 2026 20:55:09 -0300
From: Timothy Legge <timlegge@...nsec.org>
To: Cve Announce <cve-announce@...urity.metacpan.org>, Oss Security
 <oss-security@...ts.openwall.com>
Subject: CVE-2026-8376: Perl versions through 5.43.10 have a heap buffer
 overflow when compiling regular expressions with a repeated fixed string on
 32-bit builds

========================================================================
CVE-2026-8376                                        CPAN Security Group
========================================================================

         CVE ID:  CVE-2026-8376
   Distribution:  perl
       Versions:  through 5.43.10

       MetaCPAN:  https://metacpan.org/dist/perl
       VCS Repo:  https://github.com/Perl/perl5


Perl versions through 5.43.10 have a heap buffer overflow when
compiling regular expressions with a repeated fixed string on 32-bit
builds

Description
-----------
Perl versions through 5.43.10 have a heap buffer overflow when
compiling regular expressions with a repeated fixed string on 32-bit
builds.

Perl_study_chunk in regcomp_study.c checked the size of the joined
substring buffer in characters rather than bytes. For a quantified
fixed substring with a large minimum count, the byte length mincount *
l could overflow SSize_t, producing an undersized SvGROW allocation;
the subsequent copy writes past the end of the buffer.

A caller that compiles an attacker-controlled regular expression on a
32-bit perl build triggers a heap buffer overflow at compile time.

Problem types
-------------
- CWE-680 Integer Overflow to Buffer Overflow

Workarounds
-----------
On 32-bit perl builds, avoid compiling regular expressions from
untrusted input until a fixed release is installed.


Solutions
---------
Upgrade to a future perl release, or apply the upstream patch.


References
----------
https://github.com/Perl/perl5/commit/5e7f119eb2bb1181be908701f22bf7068e722f1c.patch

Timeline
--------
- 2026-04-24: Issue reported.
- 2026-05-20: Fix merged to blead.

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.