Microsoft Security Advisory CVE-2026-70179 - ASP.NET Core Elevation of Privilege Vulnerability
The source advisory has changed since this explanation was prepared. Check the current technical data and original advisory below.
Executive summary
Microsoft has released a security advisory concerning a vulnerability in Microsoft.AspNetCore.Authentication.Negotiate, along with mitigation guidance for developers.
In ASP.NET Core Negotiate LDAP authentication, an authenticated identity can be associated with an unintended LDAP principal when the LDAP result is not validated against the Kerberos principal SID.
Announcement
The original announcement for this issue is available at https://github.com/dotnet/announcements/issues/458.
CVSS Details
- Version: 3.1
- Severity: High
- Score: 7.5
- Vector:
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness: CWE-290 (Authentication Bypass by Spoofing)
Affected Platforms
- Platforms: Windows, Linux, macOS when LDAP claim resolution is enabled
- Architectures: All
Affected Packages
This vulnerability impacts Microsoft .NET projects using the following package versions:
| Package name | Affected version | Patched version |
|---|---|---|
| Microsoft.AspNetCore.Authentication.Negotiate) | >= 10.0.0, <= 10.0.12 | 10.0.13 |
| Microsoft.AspNetCore.Authentication.Negotiate) | >= 8.0.0, <= 8.0.31 | 8.0.32 |
| Microsoft.AspNetCore.Authentication.Negotiate) | >= 9.0.0, <= 9.0.20 | 9.0.21 |
Advisory FAQ
How do I know if I am affected?
Applications referencing any package versions listed in the affected packages table are exposed to this vulnerability.
How do I fix the issue?
- Install the latest version of .NET. If one or more .NET SDKs were installed through Visual Studio, Visual Studio will prompt an update that will also update the SDKs.
- If your application references a vulnerable package, update the reference to a patched version. Installed versions can be checked by running the
dotnet --infocommand.
After installing the updated runtime or SDK, restart applications for the update to take effect.
Additionally, self-contained applications) targeting affected versions must be recompiled and redeployed.
Other Information
Reporting Security Issues
Security issues in supported .NET versions can be reported to the Microsoft Security Response Center (MSRC) through the MSRC Researcher Portal.). More information is available in the MSRC Report an Issue FAQ.).
Eligible submissions may qualify for the Microsoft .NET Bounty Program; program details and conditions are published at https://aka.ms/corebounty..
Support
Questions can be directed to the .NET GitHub organization. The primary repositories are located at https://github.com/dotnet/runtime.. The Announcements repository at https://github.com/dotnet/Announcements) contains this bulletin as an issue with a link to an active discussion thread.
Disclaimer
The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
External Links
Acknowledgements
- thegoldmandm
Revisions
V1.0 (10/13/2026): Advisory published.
What to do
Update the Microsoft.AspNetCore.Authentication.Negotiate package dependency to a patched release. Install the latest .NET SDK or runtime, restart affected applications, and recompile and redeploy any self-contained deployments.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| .NET (NuGet) | Microsoft.AspNetCore.Authentication.Negotiate | >= 10.0.0, < 10.0.13, >= 8.0.0, < 8.0.32, >= 9.0.0, < 9.0.21 | 10.0.13, 8.0.32, 9.0.21 |
References
- https://github.com/dotnet/aspnetcore/security/advisories/GHSA-vrrp-6v32-2p8g
- https://github.com/dotnet/announcements/issues/458
- https://github.com/dotnet/aspnetcore
- https://github.com/dotnet/aspnetcore/discussions/69794
- https://nvd.nist.gov/vuln/detail/CVE-2026-70179
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70179
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-290- Platform
- .NET (NuGet)
- Package
Microsoft.AspNetCore.Authentication.Negotiate- Disclosed
- 13.10.2026
- Updated
- 19.10.2026 22:17
Sources and licenses · Edited or translated by DockRay; source rights and applicable licenses are retained.
OSV / GitHub Advisory Database - GHSA-vrrp-6v32-2p8g - CC BY 4.0
Vulnerability history: Microsoft.AspNetCore.Authentication.Negotiate
All published vulnerabilities of this package (.NET (NuGet)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 3
- First → latest
- 07.2026 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 3
Disclosures per year
- 2026: 3
-
Microsoft Security Advisory CVE-2026-70179 - ASP.NET Core Elevation of Privilege Vulnerability this entry
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