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

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Summary

CVECVE-2026-8796
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-31 20:16:30 UTC
Updated2026-06-01 19:16:55 UTC
DescriptionSereal::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).

Risk And Classification

Primary CVSS: v3.1 8.1 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

EPSS: 0.000150000 probability, percentile 0.034820000 (date 2026-06-02)

Problem Types: CWE-125 | CWE-125 CWE-125 Out-of-bounds Read

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED8.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary8.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA YVES SerealDecoder affected 5.005 custom Not specified

References

ReferenceSourceLinkTags
metacpan.org/release/YVES/Sereal-Decoder-5.005/changes 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
github.com/Sereal/Sereal/commit/303a2c69cdba80bf37a3ff43461e0aa78198a7a3... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
www.openwall.com/lists/oss-security/2026/06/01/1 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
CNA2026-05-13T00:00:00.000ZIssue reported.
CNA2026-05-19T00:00:00.000ZFix released in Sereal::Decoder 5.005.
CNA2026-05-20T00:00:00.000ZFix verified against proofs of concept.

Solutions

CNA: Upgrade to Sereal::Decoder 5.005 or later.

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