Inefficient Algorithmic Complexity

Overview MessagePack is a MessagePackMsgPack Serializer for C.NET, .NET Core, Unity, Xamarin. Affected versions of this package are vulnerable to Inefficient Algorithmic Complexity in the InterfaceLookupFormatter process. An attacker can cause excessive CPU consumption by supplying specially...

MessagePack-CSharp: InterfaceLookupFormatter bypasses collision-resistant comparer settings

Summary InterfaceLookupFormatter constructs an internal Dictionary with the default equality comparer instead of the security-aware comparer supplied by options.Security.GetEqualityComparer. Other hash-based collection formatters use the security-aware comparer when...

CVE-2026-48516

MessagePack for C is a MessagePack serializer for C. Prior to 2.5.301 and 3.1.7, InterfaceLookupFormatter constructs an internal Dictionary with the default equality comparer instead of the security-aware comparer supplied by options.Security.GetEqualityComparer. This formatter omission allows...

CVE-2026-48516 MessagePack-CSharp: InterfaceLookupFormatter bypasses collision-resistant comparer settings

MessagePack for C is a MessagePack serializer for C. Prior to 2.5.301 and 3.1.7, InterfaceLookupFormatter constructs an internal Dictionary with the default equality comparer instead of the security-aware comparer supplied by options.Security.GetEqualityComparer. This formatter omission allows...

CVE-2026-48516 MessagePack-CSharp: InterfaceLookupFormatter bypasses collision-resistant comparer settings

MessagePack for C is a MessagePack serializer for C. Prior to 2.5.301 and 3.1.7, InterfaceLookupFormatter constructs an internal Dictionary with the default equality comparer instead of the security-aware comparer supplied by options.Security.GetEqualityComparer. This formatter omission allows...

CVE-2026-48516 MessagePack-CSharp: InterfaceLookupFormatter bypasses collision-resistant comparer settings

MessagePack for C is a MessagePack serializer for C. Prior to 2.5.301 and 3.1.7, InterfaceLookupFormatter constructs an internal Dictionary with the default equality comparer instead of the security-aware comparer supplied by options.Security.GetEqualityComparer. This formatter omission allows...

CVE-2026-48516

MessagePack for C# (MessagePack-CSharp) prior to versions 2.5.301 and 3.1.7 constructs InterfaceLookupFormatter with a default Dictionary<TKey,IGrouping> comparer instead of the security-aware comparer from options.Security.GetEqualityComparer(). This can enable a hash-collision CPU denial-...

CVE-2026-48516: Inefficient Algorithmic Complexity

MessagePack for C is a MessagePack serializer for C. Prior to 2.5.301 and 3.1.7, InterfaceLookupFormatter constructs an internal Dictionary with the default equality comparer instead of the security-aware comparer supplied by options.Security.GetEqualityComparer . This formatter omission allows...