CVE-2026-48517

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.

Affected Software

VendorProductVersion RangeStatus
MessagePack-CSharpMessagePack-CSharp>= 3.0, < 3.1.7affected
MessagePack-CSharpMessagePack-CSharp< 2.5.301affected

Weaknesses

  • CWE-470: CWE-470: Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
  • CWE-502: CWE-502: Deserialization of Untrusted Data

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References