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-2026-48512: 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-2026-48517: 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...

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...

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-2026-48511: 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-2026-48516: 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-2026-48509: 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...

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...

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...

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...