Heap over-read via unchecked COPY back-reference
Published May 31, 2026 · Updated May 31, 2026
Out-of-bounds read in Sereal::Decoder before 5.005 allows attackers to read heap data through crafted serialized input. Within srl_read_object() and srl_read_hash(), a COPY offset can target data bytes that are reinterpreted as a SHORT_BINARY tag without bounding the encoded length before the COPY tag. Exploitation requires an application to decode attacker-supplied Sereal data and user interaction; the class-name or hash-key read can consume up to 31 bytes beyond the input buffer.
Summary
What happened
Out-of-bounds read in Sereal::Decoder before 5.005 allows attackers to read heap data through crafted serialized input. Within srl_read_object() and srl_read_hash(), a COPY offset can target data bytes that are reinterpreted as a SHORT_BINARY tag without bounding the encoded length before the COPY tag. Exploitation requires an application to decode attacker-supplied Sereal data and user interaction; the class-name or hash-key read can consume up to 31 bytes beyond the input buffer.
The record
- CVE
- CVE-2026-8796
- Published
- May 31, 2026
- Updated
- May 31, 2026
- Vendor
- Sereal
- Product
- Sereal::Decoder
- Classifications
- CWE-125
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 31, 2026CVE publishedPublication date reported by the CVE source.
- May 31, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <5.005
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream COPY SHORT_BINARY regression reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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