Messagepack vulnerabilities
We track 13 vulnerabilities in Messagepack products across 2 products. 13 are rated high or critical, and none are known to be exploited. The most recent was published on June 22, 2026.
Latest Messagepack vulnerabilities
- 7.5 High severity
MessagePack-CSharp: Use of Externally-Controlled Input to Select Classes or Code
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
- 7.5 High severity
MessagePack-CSharp: Inefficient Algorithmic Complexity
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 compar
- 7.5 High severity
MessagePack-CSharp: Allocation of Resources Without Limits or Throttling
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePack-CSharp's multi-dimensional array formatters read dimension lengths directly from the payload and allocate T[,], T[,,], or T[,,,] before validating that the dimension
- 7.5 High severity
MessagePack-CSharp: Allocation of Resources Without Limits or Throttling
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, UnsafeBlitFormatterBase<T>.Deserialize reads an attacker-controlled byteLength from an extension payload and allocates an array based on that value before validating it against
- 7.5 High severity
MessagePack-CSharp: Uncontrolled Recursion
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, runtime-generated union deserializers emitted by DynamicUnionResolver do not call MessagePackSecurity.DepthStep(ref reader) and do not decrement reader.Depth around recursive de
- 7.5 High severity
MessagePack-CSharp: Uncontrolled Recursion
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePack-CSharp's JSON conversion helpers contain multiple recursion paths that do not consistently enforce a depth limit. These paths are in the JSON conversion component ra
- 7.5 High severity
MessagePack-CSharp: Inefficient Algorithmic Complexity
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, ExpandoObjectFormatter.Deserialize populates System.Dynamic.ExpandoObject by calling IDictionary<string, object>.Add for each map entry. ExpandoObject internally maintains membe
- 7.5 High severity
MessagePack-CSharp: Improper Handling of Highly Compressed Data (Data Amplification)
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, when MessagePack-CSharp decompresses Lz4Block or Lz4BlockArray payloads, it reads declared uncompressed lengths from the wire and allocates output buffers based on those lengths
- 9.1 Critical severity
MessagePack-CSharp: Initialization of a Resource with an Insecure Default
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, the parameterless MessagePackInputFormatter() constructor uses default serializer options, which resolve to MessagePackSerializerOptions.Standard with MessagePackSecurity.Truste
- 7.5 High severity
MessagePack-CSharp: Uncontrolled Recursion
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePackReader.TrySkip() recursively descends into nested arrays and maps without incrementing the reader depth or calling the configured depth checks. This bypasses MessageP
- 7.5 High severity
MessagePack-CSharp: Out-of-bounds Read
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePackReader.ReadDateTime() can allocate stack memory based on an attacker-controlled MessagePack extension length. In the slow path for timestamp extension parsing, the co
- 8.2 High severity
MessagePack for C# is a MessagePack serializer for C#.
MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, A vulnerability exists in the optional LZ4 decompression path used by MessagePack compression modes Lz4Block and Lz4BlockArray. The decoder implementation is based on a deprecat
- 8.7 High severity
MessagePack-CSharp: Use of Weak Hash
### Impact When this library is used to deserialize messagepack data from an untrusted source, there is a risk of a denial of service attack by an attacker that sends data contrived to produce hash collisions, leading to large CPU consumption disproportionate