CVE-2026-62899: Microsoft Security Advisory CVE-2026-62899 – .NET Security Feature Bypass Vulnerability

Microsoft is releasing this security advisory to provide information about a vulnerability in System.Net.HttpListener. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

Inconsistent interpretation of http requests (‘http request/response smuggling’) in .NET allows an unauthorized attacker to bypass a security feature over a network.