EUVD-2026-38385

MessagePack-CSharp: ExpandoObject formatter can perform quadratic insertion work on untrusted maps...

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

Summary 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 distinct keys can require repeated linear scans and array copies. For large...

GHSA-2X83-8G95-XH59 MessagePack-CSharp: ExpandoObject formatter can perform quadratic insertion work on untrusted maps

Summary 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 distinct keys can require repeated linear scans and array copies. For large...

GHSA-V72X-2H86-7F8M MessagePack-CSharp: LZ4 decompression allocates from unbounded declared output lengths

Summary When MessagePack-CSharp decompresses Lz4Block or Lz4BlockArray payloads, it reads declared uncompressed lengths from the wire and allocates output buffers based on those lengths before validating that the compressed data is valid or that the declared expansion is reasonable. A small paylo...

MessagePack-CSharp: LZ4 decompression allocates from unbounded declared output lengths

Summary When MessagePack-CSharp decompresses Lz4Block or Lz4BlockArray payloads, it reads declared uncompressed lengths from the wire and allocates output buffers based on those lengths before validating that the compressed data is valid or that the declared expansion is reasonable. A small paylo...

Allocation of Resources Without Limits or Throttling

Overview MessagePack is a MessagePackMsgPack Serializer for C.NET, .NET Core, Unity, Xamarin. Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the TryDecompress process. An attacker can cause excessive memory allocation and potential...

GHSA-2F33-PR97-265Q MessagePack-CSharp: ASP.NET Core MessagePackInputFormatter defaults to TrustedData for HTTP request bodies

Summary The parameterless MessagePackInputFormatter constructor uses default serializer options, which resolve to MessagePackSerializerOptions.Standard with MessagePackSecurity.TrustedData. The formatter is designed for ASP.NET Core MVC request bodies, which commonly cross an HTTP trust boundary...

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

Summary The parameterless MessagePackInputFormatter constructor uses default serializer options, which resolve to MessagePackSerializerOptions.Standard with MessagePackSecurity.TrustedData. The formatter is designed for ASP.NET Core MVC request bodies, which commonly cross an HTTP trust boundary...

Insecure Default Initialization of Resource

Overview MessagePack is a MessagePackMsgPack Serializer for C.NET, .NET Core, Unity, Xamarin. Affected versions of this package are vulnerable to Insecure Default Initialization of Resource due to the parameterless MessagePackInputFormatter constructor using insecure default serializer options,...

EUVD-2026-38388

MessagePack-CSharp: MessagePackReader.Skip can recurse without enforcing maximum object graph depth...

Uncontrolled Recursion

Overview MessagePack is a MessagePackMsgPack Serializer for C.NET, .NET Core, Unity, Xamarin. Affected versions of this package are vulnerable to Uncontrolled Recursion in the Skip process. An attacker can cause the application to terminate unexpectedly by submitting specially crafted MessagePack...

MessagePack-CSharp: MessagePackReader.Skip can recurse without enforcing maximum object graph depth

Summary MessagePackReader.TrySkip recursively descends into nested arrays and maps without incrementing the reader depth or calling the configured depth checks. This bypasses MessagePackSecurity.MaximumObjectGraphDepth, the library's documented protection against deeply nested object graphs. Many...

GHSA-VH6J-JC39-FGGF MessagePack-CSharp: MessagePackReader.Skip can recurse without enforcing maximum object graph depth

Summary MessagePackReader.TrySkip recursively descends into nested arrays and maps without incrementing the reader depth or calling the configured depth checks. This bypasses MessagePackSecurity.MaximumObjectGraphDepth, the library's documented protection against deeply nested object graphs. Many...

EUVD-2026-38389

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

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

Summary MessagePackReader.ReadDateTime can allocate stack memory based on an attacker-controlled MessagePack extension length. In the slow path for timestamp extension parsing, the computed tokenSize includes the extension body length from the wire and is used in a stackalloc operation before the...

GHSA-382J-8MXH-C7X2 MessagePack-CSharp: Denial of service vulnerabilities can swamp the CPU or crash the process with stack and heap overflows

Summary MessagePackReader.ReadDateTime can allocate stack memory based on an attacker-controlled MessagePack extension length. In the slow path for timestamp extension parsing, the computed tokenSize includes the extension body length from the wire and is used in a stackalloc operation before the...

dotnet: ASP.NET Core: Denial of Service via uncontrolled resource consumption

A flaw was found in ASP.NET Core SignalR and Blazor Server. A remote attacker could send a specially crafted MessagePack payload containing deeply nested arrays that trigger excessive recursion and cause a stack overflow. This issue may result in application termination and a denial of service...

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-2026-48514

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 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...