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CVE PROGRAM SOURCE RECORD6.3 Medium

CVE-2026-48510

MessagePack-CSharp: LZ4 decompression allocates from unbounded declared output lengths

Description

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, when MessagePack-CSharp decompresses Lz4Block or Lz4BlockArray payloads, it reads declared uncompressed lengths from the wire and allocates output buffers based on those lengths before validating that the compressed data is valid or that the declared expansion is reasonable. A small payload can claim a very large uncompressed length and force a large allocation before LZ4 decoding begins. This vulnerability is fixed in 2.5.301 and 3.1.7.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

MessagePack-CSharp MessagePack-CSharp

  • >= 3.0, < 3.1.7affected
  • < 2.5.301affected

References