CVE-2026-15534

Name	CVE-2026-15534
Description	Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch. The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it. A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1144413

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
perl (PTS)	bullseye	5.32.1-4+deb11u3	vulnerable
	bullseye (security)	5.32.1-4+deb11u5	vulnerable
	bookworm	5.36.0-7+deb12u3	vulnerable
	bookworm (security)	5.36.0-7+deb12u2	vulnerable
	trixie	5.40.1-6	vulnerable
	forky, sid	5.42.3-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
perl	source	(unstable)	(unfixed)			1144413

Notes

[trixie] - perl <postponed> (Wait for exposure unstable and coordinate with Perl maintainers)
https://lists.security.metacpan.org/cve-announce/msg/42536248/
Fixed by: https://github.com/Perl/perl5/commit/568e6fd238867bb9e99fa3f47cba3169009239e0
Fixed by: https://github.com/Perl/perl5/commit/54cf3d44cbbedd17d774e9a37921963e8fd5d0cb