Back to overview

CVE-2026-48509

MEDIUM
6.3
CVSS 4.0
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.

Metadata

CVE ID
CVE-2026-48509
State
PUBLISHED
Assigner
GitHub_M
Reserved
2026-05-21 16:18 UTC
Published
2026-06-22 21:16 UTC
Last updated
2026-06-22 21:16 UTC
Primary CWE
CWE-1188
CWE-1188: Insecure Default Initialization of Resource
Vendor / Product
MessagePack-CSharp / MessagePack-CSharp
Sources
cve.org  ·  NVD

Severity & Metrics

6.3 MEDIUM CVSS 4.0
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
Affected products (1)
VendorProductPlatformVersions
MessagePack-CSharp MessagePack-CSharp — >= 3.1.7, < 3.1.7, < 2.5.301
Weakness (CWE)
CWESourceDescription
CWE-1188 cna CWE-1188: Insecure Default Initialization of Resource
CVSS scores (1)
ScoreSeverityVersionSourceVector
6.3 MEDIUM 4.0 cna CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
References (1)
Back to overview