CVE-2026-8796

Name	CVE-2026-8796
Description	Sereal::Decoder versions before 5.005 for Perl allow heap out-of-bounds read via crafted input. In Perl/Decoder/srl_decoder.c, srl_read_object() and srl_read_hash() process a COPY tag, a back-reference whose target byte the decoder re-decodes as a fresh tag. When that target byte matches the SHORT_BINARY pattern (an inline string whose length is encoded in the low bits of the tag), the resulting read is not bounded to precede the COPY tag's own offset and can run past the end of the input buffer. An attacker controlled COPY offset can land inside a previously decoded value rather than on a tag boundary, planting a byte that the decoder reads as a SHORT_BINARY tag and consuming up to 31 following bytes from the heap as a class name (OBJECT path) or hash key (HASH path).
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	1138633

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libsereal-decoder-perl (PTS)	bullseye	4.018+ds-1	vulnerable
	bookworm	5.003+ds-1	vulnerable
	forky, trixie	5.004+ds-1	vulnerable
	sid	5.006+ds-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libsereal-decoder-perl	source	(unstable)	5.006+ds-1			1138633

Notes

[trixie] - libsereal-decoder-perl <no-dsa> (Minor issue)
[bookworm] - libsereal-decoder-perl <no-dsa> (Minor issue)
https://lists.security.metacpan.org/cve-announce/msg/40571630/
Fixed by: https://github.com/Sereal/Sereal/commit/303a2c69cdba80bf37a3ff43461e0aa78198a7a3 (Sereal-5.005)