CVE-2024-21643: Microsoft Identitymodel Extensions

High severity, CVSS 8.8. EPSS: 2.2% chance of exploitation in the next 30 days.

IdentityModel Extensions for .NET provide assemblies for web developers that wish to use federated identity providers for establishing the caller's identity. Anyone leveraging the `SignedHttpRequest`protocol or the `SignedHttpRequestValidator`is vulnerable. Microsoft.IdentityModel trusts the `jku`claim by default for the `SignedHttpRequest`protocol. This raises the possibility to make any remote or local `HTTP GET` request. The vulnerability has been fixed in Microsoft.IdentityModel.Protocols.SignedHttpRequest. Users should update all their Microsoft.IdentityModel versions to 7.1.2 (for 7x) or higher, 6.34.0 (for 6x) or higher.

Affected products

• Microsoft Identitymodel Extensions: before 6.34.0 (fixed in 6.34.0); from 7.0.0, before 7.1.2 (fixed in 7.1.2)

Published 2024-01-10. Last modified 2026-06-17.