CPANSA--2026-8796: Sereal-Decoder vulnerability
| Publisher | giterlizzi | Document category | csaf_security_advisory |
|---|---|---|---|
| Initial release date | 2026-05-31T00:00:00 | Engine | CSAF Perl Toolkit 0.26 |
| Current release date | 2026-05-31T00:00:00 | Build Date | |
| Current version | 1 | Status | final |
| CVSS v3.1 Base Score | 8.1 | Severity | |
| Original language | Language | en | |
| Also referred to | |||
Vulnerability 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).
Vulnerabilities
CVE-2026-8796
Vulnerability 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).
| Weakness | CWE-125 : Out-of-bounds Read |
|---|
Product status
Known affected
| Product | Score | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Sereal-Decoder less than 5.005 |
|
Fixed
- Sereal-Decoder greater than or equal 5.005
giterlizzi
Namespace: https://github.com/giterlizzi/
gdt@cpan.org
References
- CPANSA--2026-8796 JSON self
https://raw.githubusercontent.com/giterlizzi/perl-CPANSA-CSAF/develop/csaf/white/2026/cpansa--2026-8796.json - https://github.com/Sereal/Sereal/commit/303a2c69cdba80bf37a3ff43461e0aa78198a7a3.patch external
https://github.com/Sereal/Sereal/commit/303a2c69cdba80bf37a3ff43461e0aa78198a7a3.patch - https://metacpan.org/release/YVES/Sereal-Decoder-5.005/changes external
https://metacpan.org/release/YVES/Sereal-Decoder-5.005/changes - http://www.openwall.com/lists/oss-security/2026/06/01/1 external
http://www.openwall.com/lists/oss-security/2026/06/01/1 - CVE-2026-8796 (NVD) external
https://nvd.nist.gov/vuln/detail/CVE-2026-8796
Revision history
| Version | Date of the revision | Summary of the revision |
|---|---|---|
| 1 | Sun May 31 00:00:00 2026 | First release |
Sharing rules
TLP:WHITE
For the TLP version see: https://www.first.org/tlp/