Description

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, A vulnerability exists in the optional LZ4 decompression path used by MessagePack compression modes Lz4Block and Lz4BlockArray. The decoder implementation is based on a deprecated fast-decompression algorithm that does not take a source-length bound. A remote attacker can send a crafted MessagePack payload with manipulated LZ4 token/length fields to force out-of-bounds reads from the compressed input buffer. In affected environments, this can trigger an AccessViolationException during decompression, causing process termination (denial of service). Under some conditions, limited unintended memory disclosure from over-read data may also be possible before failure. This vulnerability is fixed in 2.5.301 and 3.1.7.

Severity (CVSS)

Base score8.2
SeverityHigh
VersionCVSS 3.1
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Provided byCNA

Weaknesses

  • CWE-20 — CWE-20: Improper Input Validation

Affected products

VendorProductVersions
MessagePack-CSharpMessagePack-CSharp>= 3.1.7, < 3.1.7; < 2.5.301

References

Authoritative sources

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Generated from the official CVE List on 23 Jun 2026 10:05 UTC.