GHSA-CJ9G-3MJ2-G8VV MessagePack-CSharp: JSON conversion APIs can recurse without consistent depth enforcement

Summary 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 rather than normal typed MessagePack deserialization. Three related issues are covered by this advisory: 1...

EUVD-2026-38389

MessagePack-CSharp: Denial of service vulnerabilities can swamp the CPU or crash the process with stack and heap overflows...

CVE-2026-48109 MessagePack-CSharp: LZ4 decompression may fail with AccessViolationException after dereferencing memory from bad input

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 deprecated fast-decompression algorithm that do...

CVE-2026-48109

CVE-2026-48109 affects MessagePack-CSharp in the optional LZ4 decompression path (Lz4Block, Lz4BlockArray). The vulnerability stems from a deprecated fast-decompression algorithm that does not enforce a source-length bound, enabling a remote attacker to craft payloads with manipulated LZ4 token/l...

CVE-2026-48506

The CVE-2026-48506 entry concerns MessagePack-CSharp: MessagePackReader.TrySkip() can recurse without incrementing depth checks, bypassing MaximumObjectGraphDepth and risking unbounded recursion leading to StackOverflow. Affected: MessagePack-CSharp (reader Skip usage in nested arrays/maps). Root...

CVE-2026-48509

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.TrustedData. The formatter is designed for...

CVE-2026-48509 MessagePack-CSharp: ASP.NET Core MessagePackInputFormatter defaults to TrustedData for HTTP request bodies

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.TrustedData. The formatter is designed for...

CVE-2026-48509

CVE-2026-48509 affects MessagePack for C# (ASP.NET Core MVC context). The issue is that, prior to versions 2.5.301 and 3.1.7, the parameterless MessagePackInputFormatter() uses default serializer options that resolve to Standard with MessagePackSecurity.TrustedData, which can cross HTTP trust bou...

CVE-2026-48511 MessagePack-CSharp: ExpandoObject formatter can perform quadratic insertion work on untrusted maps

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.Add for each map entry. ExpandoObject internally maintains member names in array-like structures, so inserting many...

CVE-2026-48512 MessagePack-CSharp: JSON conversion APIs can recurse without consistent depth enforcement

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 rather than normal typed MessagePack...

CVE-2026-48512 MessagePack-CSharp: JSON conversion APIs can recurse without consistent depth enforcement

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 rather than normal typed MessagePack...

CVE-2026-48512

CVE-2026-48512 affects MessagePack-CSharp. The JSON conversion helpers in MessagePack-CSharp allowed recursive processing without a consistent depth limit, enabling attacker-controlled input to exhaust the process stack and trigger a StackOverflowException. This occurs in the JSON conversion path...

CVE-2026-48514 MessagePack-CSharp: Unity unsafe blit formatter allocates from unbounded byte length

MessagePack for C is a MessagePack serializer for C. Prior to 2.5.301 and 3.1.7, UnsafeBlitFormatterBase.Deserialize reads an attacker-controlled byteLength from an extension payload and allocates an array based on that value before validating it against the extension header length or remaining...

CVE-2026-48514 MessagePack-CSharp: Unity unsafe blit formatter allocates from unbounded byte length

MessagePack for C is a MessagePack serializer for C. Prior to 2.5.301 and 3.1.7, UnsafeBlitFormatterBase.Deserialize reads an attacker-controlled byteLength from an extension payload and allocates an array based on that value before validating it against the extension header length or remaining...

CVE-2026-48515 MessagePack-CSharp: Multi-dimensional array formatters allocate from unchecked dimensions

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 product matches the encoded element count. T...

CVE-2026-48515

Summary: CVE-2026-48515 affects MessagePack-CSharp. Before versions 2.5.301 and 3.1.7, multi-dimensional array formatters allocate T[,] / T[,,] / T[,,,] using dimension lengths read from the payload before validating the encoded element count, enabling large heap allocations. Impact: potential hi...

CVE-2026-48517 MessagePack-CSharp: Typeless deserialization type restrictions do not recurse into arrays or generic arguments

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.ThrowIfDeserializingTypeIsDisallowedType as a safety check for dangerous types. The default implementation checks the outer type nam...

CVE-2026-48517 MessagePack-CSharp: Typeless deserialization type restrictions do not recurse into arrays or generic arguments

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.ThrowIfDeserializingTypeIsDisallowedType as a safety check for dangerous types. The default implementation checks the outer type nam...

CVE-2026-48517

CVE-2026-48517 affects MessagePack-CSharp (MessagePack for C#). The vulnerability arises because typeless deserialization’s safety check (ThrowIfDeserializingTypeIsDisallowed) only validates the outer type name and does not recursively inspect inner types such as array element types or generic ty...

PT-2026-51397

Name of the Vulnerable Software and Affected Versions MessagePack for C versions prior to 2.5.301 MessagePack for C versions prior to 3.1.7 Description Runtime-generated union deserializers emitted by DynamicUnionResolver fail to call MessagePackSecurity.DepthStepref reader and do not decrement...