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CVE PROGRAM SOURCE RECORD6.3 Medium

CVE-2026-48515

MessagePack-CSharp: Multi-dimensional array formatters allocate from unchecked dimensions

Description

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePack-CSharp's multi-dimensional array formatters read dimension lengths directly from the payload and allocate T[,], T[,,], or T[,,,] before validating that the dimension product matches the encoded element count. The formatter reads a guarded element array header, but allocation of the target multi-dimensional array happens before the dimensions are checked against that element count. A small payload can therefore declare large dimensions, provide an empty or tiny inner array, and cause a large heap allocation before element data is validated. 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