CVE-2026-8796: Sereal::Decoder versions before 5.005 for Perl allow heap out-of-bounds read via crafted input

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-31 · updated 2026-07-22
Weakness: CWE-125

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).

Affected products

YVES Sereal::Decoder: before 5.005 — fixed in 5.005

How to fix

Upgrade to a fixed version: YVES Sereal::Decoder 5.005. Check the vendor advisory for mitigations.

References

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