Skip to content
CVE PROGRAM SOURCE RECORD6.3 Medium

CVE-2026-48516

MessagePack-CSharp: InterfaceLookupFormatter bypasses collision-resistant comparer settings

Description

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, InterfaceLookupFormatter<TKey,TElement> constructs an internal Dictionary<TKey, IGrouping<TKey,TElement>> with the default equality comparer instead of the security-aware comparer supplied by options.Security.GetEqualityComparer<TKey>(). This formatter omission allows hash-collision CPU denial of service against ILookup<TKey,TElement> even when the application has opted into the untrusted-data security posture 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