A security feature bypass vulnerability exists when Active Directory Federation Services…
Priority LOW 39Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- No fix listed
Attack profile from CVSS 3.0 · NVD. Fix status from CNA.
Summary
A security feature bypass vulnerability exists when Active Directory Federation Services (AD FS) improperly handles multi-factor authentication requests, aka "AD FS Security Feature Bypass Vulnerability." This affects Windows Server 2016, Windows Server 2012 R2, Windows 10 Servers.
Why it matters now
EPSS 0.07887 94th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Microsoft | Windows Server 2016 | (Server Core installation) | — | No fix listed | CNA |
| Microsoft | Windows Server 2012 R2 | (Server Core installation) | — | No fix listed | CNA |
| Microsoft | Windows 10 Servers | version 1709 (Server Core Installation); version 1803 (Server Core Installation) | — | No fix listed | CNA |
- Windows Server 2016 VendorMicrosoft Affected (Server Core installation) Fixed in — No fix listed CNA
- Windows Server 2012 R2 VendorMicrosoft Affected (Server Core installation) Fixed in — No fix listed CNA
- Windows 10 Servers VendorMicrosoft Affected version 1709 (Server Core Installation); version 1803 (Server Core Installation) Fixed in — No fix listed CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:* | r2 | Vulnerable | Microsoft |
| cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | Microsoft |
| cpe:2.3:o:microsoft:windows_server_2016:1709:*:*:*:*:*:*:* | 1709 | Vulnerable | Microsoft |
| cpe:2.3:o:microsoft:windows_server_2016:1803:*:*:*:*:*:*:* | 1803 | Vulnerable | Microsoft |
- cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:* Versions r2 Vulnerable ·Microsoft
- cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
- cpe:2.3:o:microsoft:windows_server_2016:1709:*:*:*:*:*:*:* Versions 1709 Vulnerable ·Microsoft
- cpe:2.3:o:microsoft:windows_server_2016:1803:*:*:*:*:*:*:* Versions 1803 Vulnerable ·Microsoft
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2018-8340
- 2026-10-03 Alias added: GHSA-4rgc-rj2m-g9gr
More Microsoft Windows Server 2012 vulnerabilities
- TI-2025-36863 Windows Server Update Service (WSUS) Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
- TI-2020-01431 Netlogon Elevation of Privilege Vulnerability KEVCVSS 3.1CRITICAL 10.0
- TI-2020-01310 Improper input validation in Microsoft Windows Server KEVCVSS 3.1CRITICAL 10.0
- TI-2017-06077 Microsoft Windows XP SP3, Windows XP x64 XP2, Windows Server 2003 SP2, Windows Vista… KEVCVSS 3.1CRITICAL 9.8
- TI-2015-01465 HTTP.sys in Microsoft Windows 7 SP1, Windows Server 2008 R2 SP1, Windows 8, Windows 8.1… KEVCVSS 3.1CRITICAL 9.8
- TI-2020-01009 Improper input validation in Microsoft Windows Server KEVCVSS 3.1CRITICAL 9.0
Sources
- CVE-2018-8340 · CVE Program
- CVE-2018-8340 · NVD
- FIRST EPSS
- GHSA-4rgc-rj2m-g9gr · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences