Affected: MessagePack-CSharp

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.303 and 3.1.9, deserializing attacker-controlled MessagePack data as System.Object through PrimitiveObjectFormatter can cause excessive memory allocation. The formatter allocates an object[] from each declared array length before the configured object-graph depth limit rejects the input, while nested array headers can reuse the same trailing unread bytes to satisfy per-header length validation. A comparatively small payload can therefore keep many large arrays alive at once. When an attacker can submit such data repeatedly, the allocations can cause severe managed-heap pressure, excessive garbage collection, process termination, or loss of service. Exposure requires an application to deserialize untrusted data through the affected formatter path and permit repeated attacker-controlled submissions, such as a reachable ASP.NET Core SignalR hub method with an object parameter and AddMessagePackProtocol() enabled. This issue is fixed in versions 2.5.303 and 3.1.9.

Affected: Ubuntu:22.04:LTS: dotnet8, Ubuntu:24.04:LTS: dotnet10, Ubuntu:24.04:LTS: dotnet8, Ubuntu:26.10: dotnet10, Ubuntu:26.10: dotnet11, Ubuntu:26.04:LTS: dotnet10

Multiple security issues were discovered in .NET and this update includes new upstream .NET versions to fix these issues.

.NET 8 has been updated to 8.0.32 in Ubuntu 22.04 LTS and Ubuntu 24.04 LTS. .NET 10 has been updated to 10.0.13 in Ubuntu 24.04 LTS, Ubuntu 26.04 LTS and Ubuntu 26.10. .NET 11 has been updated to 11.0.0~rc2 in Ubuntu 26.10.

In addition to security fixes, the updated packages contain bug fixes, new features, and possibly incompatible changes.