Findings

CVE-2026-70179

Microsoft Security Advisory CVE-2026-70179 - ASP.NET Core Elevation of Privilege Vulnerability

Published Oct 13, 2026 · updated Oct 13, 2026

## Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in Microsoft.AspNetCore.Authentication.Negotiate. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability. ASP.NET Core Negotiate LDAP authentication can associate an authenticated identity with an unintended LDAP principal when the LDAP result is not verified against the Kerberos principal SID. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/458 ## CVSS Details - **Version:** 3.1 - **Severity:** High - **Score:** 7.5 - **Vector:** - **Weakness:** CWE-290 (Authentication Bypass by Spoofing) ## Affected Platforms - **Platforms:** Windows, Linux, macOS when LDAP claim resolution is enabled - **Architectures:** All ## Affected Packages The vulnerability affects Microsoft .NET projects that use an affected package version listed below. Package name | Affected version | Patched version ------------ | ---------------- | --------------- [Microsoft.AspNetCore.Authentication.Negotiate](https://www.nuget.org/packages/Microsoft.AspNetCore.Authentication.Negotiate) | >= 10.0.0, = 8.0.0, = 9.0.0, How do I know if I am affected? If using a package listed in [affected packages](#affected-packages), you're exposed to the vulnerability. ### How do I fix the issue? 1. To fix the issue please install the latest version of .NET. If you have installed one or more .NET SDKs through Visual Studio, Visual Studio will prompt you to update Visual Studio, which will also update your .NET SDKs. 2. If your application references the vulnerable package, update the package reference to the patched version. You can list the versions you have installed by running the command. Once you have installed the updated runtime or SDK, restart your apps for the update to take effect. Additionally, if you've deployed [self-contained applications](https://docs.microsoft.com/dot