Executive brief
A security vulnerability has been identified in Microsoft .NET, a widely used framework for building and running applications. This flaw affects how the system handles secure web connections (TLS/SSL handshakes). An attacker could exploit this to crash an application or make it unresponsive, leading to a denial of service. Organizations should update their .NET runtimes and SDKs to the latest patched versions to maintain service availability.
Technical details
A denial of service (DoS) vulnerability exists in the .NET TLS/SSL implementation within the System.Net.Security namespace. The issue is classified as an improper validation of specified type of input (CWE-1287). An unauthenticated remote attacker can trigger this vulnerability by sending malformed requests during the TLS handshake process. Successful exploitation causes the affected application to crash or become unresponsive. The vulnerability impacts .NET 8, 9, and 10 across all platforms and architectures. Microsoft has released patches in versions 8.0.29, 9.0.18, and 10.0.10.
Affected products
- Microsoft .NET 8.0.0 - 8.0.28, 9.0.0 - 9.0.17, 10.0.0 - 10.0.9
Timeline
- 2026-07-14: disclosed
- 2026-07-14: patched
- 2026-07-20: advisory
References
- https://github.com/dotnet/runtime/security/advisories/GHSA-w7cw-xp7h-6j5j
- https://github.com/dotnet/announcements/issues/413
- https://github.com/dotnet/runtime/issues/130710
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50524
- https://api.github.com/repos/dotnet/runtime/security-advisories/GHSA-w7cw-xp7h-6j5j