Microsoft Security Advisory CVE-2026-47300 – .NET Elevation of Privilege Vulnerability

Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core Negotiate Authentication Microsoft.AspNetCore.Authentication.Negotiate. This advisory also provides guidance on what developers can do to update their applications to remov...

Incorrect Authorization

Overview Affected versions of this package are vulnerable to Incorrect Authorization via improper validation in the ASP.NET Core Negotiate authentication handler. An attacker with valid credentials can elevate privileges by supplying crafted authentication data that bypasses intended validation...