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

CVE-2026-8796 is fixed in 4 products on 1 platform, first by ALAS2023-2026-1830, released June 11, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-8796
- Priority: High
- CVSS: 8.1 (high)
- EPSS: 0.0040
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 31, 2026

## 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).

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libsereal-decoder-perl Debian 14 | 5.006+ds-1 | [DEBIAN-CVE-2026-8796](https://patchblox.com/security/data/fix/linux/debian-cve-2026-8796.md) | Jun 24, 2026 |
| Linux | perl-Sereal-Decoder amzn 2023 | 4.018-2.amzn2023.0.4 | [ALAS2023-2026-1830](https://patchblox.com/security/data/fix/linux/alas2023-2026-1830.md) | Jun 11, 2026 |
| Linux | perl-Sereal-Decoder-debuginfo amzn 2023 | 4.018-2.amzn2023.0.4 | [ALAS2023-2026-1830](https://patchblox.com/security/data/fix/linux/alas2023-2026-1830.md) | Jun 11, 2026 |
| Linux | perl-Sereal-Decoder-debugsource amzn 2023 | 4.018-2.amzn2023.0.4 | [ALAS2023-2026-1830](https://patchblox.com/security/data/fix/linux/alas2023-2026-1830.md) | Jun 11, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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