CVE-2026-50528: .NET SslStream TLS Authorization Bypass
A flaw in .NET's SslStream lets a remote, unauthenticated attacker bypass authorization checks on TLS connections, potentially reading confidential data or tampering with protected traffic.
The problem
The vulnerability lives in System.Net.Security.SslStream, the component .NET uses to wrap network streams with TLS/SSL. An attacker on the network can trigger the bypass without credentials or user interaction.
The CVSS vector (AV:N/AC:L/PR:N/UI:N) confirms zero-friction exploitation: no auth, no special access, low complexity. Impact is high on integrity and low on confidentiality, meaning an attacker can manipulate data protected by the TLS channel.
The fix
Update to the patched runtime for your track: .NET 8 users upgrade to 8.0.29, .NET 9 users to 9.0.18, and .NET 10 users to 10.0.10. Run 'dotnet --info' to confirm your installed version. Self-contained deployments must be recompiled and redeployed against the patched SDK.
If you use Visual Studio, accept the prompted Visual Studio update, which pulls in the corrected SDK automatically.
Reported by Henrique Pereira (Microsoft) and Ky0toFu.
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