CVE-2026-48509
MessagePack-CSharp: ASP.NET Core MessagePackInputFormatter defaults to TrustedData for HTTP request bodies
Severity by source
Trivy's own label is CRITICAL. Rated critical by NVD. Rated lower by GHSA (medium).
Description
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 ASP.NET Core MVC request bodies, which commonly cross an HTTP trust boundary. This insecure default can expose applications to denial-of-service attacks that MessagePackSecurity.UntrustedData is intended to mitigate, such as hash-collision attacks against dictionary-like model properties. This vulnerability is fixed in 2.5.301 and 3.1.7.
Affected packages and fixed versions
| Source | Package | Fixed in |
|---|---|---|
| nuget::GitHub Security Advisory NuGet | MessagePack, messagepack | 2.5.301, 3.1.7 |
Show all 2 entries from 1 source
| Source | Package | Fixed in |
|---|---|---|
| nuget::GitHub Security Advisory NuGet | MessagePack | 2.5.301, 3.1.7 |
| nuget::GitHub Security Advisory NuGet | messagepack | 2.5.301, 3.1.7 |