PT-2026-51392

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 The MessagePackReader.TrySkip function recursively descends into nested arrays and maps without incrementing the reader depth or triggering...

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...

CVE-2026-48511: 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 .Add for each map entry. ExpandoObject internally maintains member names in array-like structures, so inserting many...

CVE-2026-48109: Improper Input Validation

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-2026-48517: 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.ThrowIfDeserializingTypeIsDisallowedType as a safety check for dangerous types. The default implementation checks the outer type nam...

CVE-2026-48512: 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 rather than normal typed MessagePack...

CVE-2026-48509: 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.TrustedData. The formatter is designed for...

PT-2026-51401

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 Typeless deserialization in MessagePack-CSharp uses MessagePackSerializerOptions.ThrowIfDeserializingTypeIsDisallowedType to prevent the...

GHSA-6V7P-G79W-8964 MessagePack for Python: Out-of-bounds read / crash on Unpacker reuse after a caught error

Impact If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV. If the Unpacker is used repeatedly to unpack untrusted input from external sources, it may be vulnerable to a DoS attack. Patches v1.2.1 Workarounds Users should create a new Unpacker instead of...

MessagePack for Python: Out-of-bounds read / crash on Unpacker reuse after a caught error

Impact If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV. If the Unpacker is used repeatedly to unpack untrusted input from external sources, it may be vulnerable to a DoS attack. Patches v1.2.1 Workarounds Users should create a new Unpacker instead of...

PT-2026-54004

Name of the Vulnerable Software and Affected Versions MessagePack versions prior to 1.2.1 Description An out-of-bounds read occurs when an Unpacker is reused after an error has been caught, which can lead to a denial of service DoS attack. If the Unpacker is used repeatedly following such an erro...

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...

Microsoft Security Advisory CVE-2026-45591 – ASP.NET Core Denial of Service Vulnerability

Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core SignalR and Blazor Server. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. A denial of service...

GHSA-F8H2-VMM9-QHJ6 Microsoft Security Advisory CVE-2026-45591 – ASP.NET Core Denial of Service Vulnerability

Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core SignalR and Blazor Server. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. A denial of service...

Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS : .NET vulnerabilities (USN-8420-1)

The remote Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8420-1 advisory. It was discovered that .NET did not properly handle link resolution before file access. A local attacker could use this...

GHSA-HV8M-JJ95-WG3X MessagePack's LZ4 decompression may fail with AccessViolationException after dereferencing memory from bad input

Impact 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 does not take a source-length bound. A remote attacker can send a crafted...

MessagePack's LZ4 decompression may fail with AccessViolationException after dereferencing memory from bad input

Impact 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 does not take a source-length bound. A remote attacker can send a crafted...

Out-of-bounds Read

Overview MessagePack is a MessagePackMsgPack Serializer for C.NET, .NET Core, Unity, Xamarin. Affected versions of this package are vulnerable to Out-of-bounds Read in the LZ4 decompression path for Lz4Block and Lz4BlockArray modes. An attacker can cause process termination or potentially access...

USN-8420-1 dotnet8, dotnet9, dotnet10 vulnerabilities

It was discovered that .NET did not properly handle link resolution before file access. A local attacker could use this issue to perform unauthorized file tampering and write arbitrary files outside of the intended extraction directory. CVE-2026-45491 It was discovered that .NET did not properly...

USN-8420-1: .NET vulnerabilities

It was discovered that .NET did not properly handle link resolution before file access. A local attacker could use this issue to perform unauthorized file tampering and write arbitrary files outside of the intended extraction directory. CVE-2026-45491 It was discovered that .NET did not properly...