CVE-2026-70179
High CVSS 7.5Published 2026-10-13 ยท last changed 2026-10-13
The fix
Microsoft publishes remediation for this across 3 product branches. The fixed build differs per Windows version, so the row that matters is the one matching the machine you are looking at.
| Windows version | Fixed in build | Update | Released |
|---|---|---|---|
| Microsoft.AspNetCore.Authentication.Negotiate on .NET 10.0 installed on Windows | 10.0.13 | configuration change | 2026-10-13 |
| Microsoft.AspNetCore.Authentication.Negotiate on .NET 8.0 installed on Windows | 8.0.32 | configuration change | 2026-10-13 |
| Microsoft.AspNetCore.Authentication.Negotiate on .NET 9.0 installed on Windows | 9.0.21 | configuration change | 2026-10-13 |
Having the KB is not the same as knowing whether a machine has it. Windows updates supersede each other, so the update you installed often covers a fix that shipped in an earlier one. Paste your build into the patch checker and it walks that chain for you.
What it is
Authentication bypass by spoofing in ASP.NET Core allows an authorized attacker to elevate privileges over a network.
Sources
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H