CVE-2026-48509 - Medium Severity Vulnerability
Vulnerable Library - messagepack.3.1.4.nupkg
Extremely Fast MessagePack(MsgPack) Serializer for C# (.NET Framework, .NET 6, Unity, Xamarin).
Library home page: https://api.nuget.org/packages/messagepack.3.1.4.nupkg
Path to dependency file: /src/SharpConnector.Tests/SharpConnector.Tests.csproj
Path to vulnerable library: /home/wss-scanner/.nuget/packages/messagepack/3.1.4/messagepack.3.1.4.nupkg,/home/wss-scanner/.nuget/packages/messagepack/3.1.4/messagepack.3.1.4.nupkg,/home/wss-scanner/.nuget/packages/messagepack/3.1.4/messagepack.3.1.4.nupkg
Dependency Hierarchy:
- enyimmemcachedcore.3.5.0.nupkg (Root Library)
- ❌ messagepack.3.1.4.nupkg (Vulnerable Library)
Found in base branch: develop
Vulnerability Details
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.
Publish Date: 2026-06-22
URL: CVE-2026-48509
CVSS 3 Score Details (4.8)
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: High
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: Low
- Availability Impact: Low
For more information on CVSS3 Scores, click here.
Suggested Fix
Type: Upgrade version
Origin: GHSA-2f33-pr97-265q
Release Date: 2026-06-22
Fix Resolution: messagepack - 2.5.301,messagepack - 3.1.7,MessagePack - 3.1.7,MessagePack - 2.5.301
Step up your Open Source Security Game with Mend here
CVE-2026-48509 - Medium Severity Vulnerability
Extremely Fast MessagePack(MsgPack) Serializer for C# (.NET Framework, .NET 6, Unity, Xamarin).
Library home page: https://api.nuget.org/packages/messagepack.3.1.4.nupkg
Path to dependency file: /src/SharpConnector.Tests/SharpConnector.Tests.csproj
Path to vulnerable library: /home/wss-scanner/.nuget/packages/messagepack/3.1.4/messagepack.3.1.4.nupkg,/home/wss-scanner/.nuget/packages/messagepack/3.1.4/messagepack.3.1.4.nupkg,/home/wss-scanner/.nuget/packages/messagepack/3.1.4/messagepack.3.1.4.nupkg
Dependency Hierarchy:
Found in base branch: develop
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.
Publish Date: 2026-06-22
URL: CVE-2026-48509
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: High
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: Low
- Availability Impact: Low
For more information on CVSS3 Scores, click here.Type: Upgrade version
Origin: GHSA-2f33-pr97-265q
Release Date: 2026-06-22
Fix Resolution: messagepack - 2.5.301,messagepack - 3.1.7,MessagePack - 3.1.7,MessagePack - 2.5.301
Step up your Open Source Security Game with Mend here