CVE-2026-48516
MessagePack-CSharp: InterfaceLookupFormatter bypasses collision-resistant comparer settings
CVSS Score
0.0
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-407 |
| Vendor | messagepack-csharp |
| Product | messagepack-csharp |
| Published | Jun 22, 2026 |
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Affected Versions
MessagePack-CSharp / MessagePack-CSharp
>= 3.1.7, < 3.1.7 < 2.5.301