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CVE-2026-48517GHSA-QHMF-XW27-6RQR

MessagePack-CSharp: Typeless deserialization type restrictions do not recurse into arrays or generic arguments

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.1.7, 2.5.301
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePack-CSharp's typeless deserialization includes MessagePackSerializerOptions.ThrowIfDeserializingTypeIsDisallowed(Type) as a safety check for dangerous types. The default implementation checks the outer type name, but it does not recursively inspect array element types or generic type arguments. As a result, a type that would be blocked directly can be wrapped inside an array or constructed generic type and pass the outer type check. The formatter machinery can then materialize formatters for the inner blocked type. This vulnerability is fixed in 2.5.301 and 3.1.7.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • MessagePack-CSharp MessagePack-CSharp

    From 3.0 · fixed in 3.1.7; fixed in 2.5.301

  • MessagePackNuGet

    fixed in 2.5.301

  • MessagePackNuGet

    From 3.0 · fixed in 3.1.7

References 1

GitHub · MessagePack-CSharp/MessagePack-CSharp