CVE-2026-42911Important
Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
Assessment
Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
- Severity
- Important
- CVSS base score
- 7.0CVSS:3.1/
AV:L/ AC:H/ PR:L/ UI:N/ S:U/ C:H/ I:H/ A:H/ E:U/ RL:O/ RC:C - Impact
- Elevation of Privilege
- EPSS, next 30 days
- 0.3%Higher than 16.4% of scored CVEs · FIRST model run 29 Sep 2026 · about EPSS
- Public exploit code
- No Nuclei template lists it
- Exploitability
- Exploitation Less Likely
- Publicly disclosed
- No
- Customer action
- Required: apply the update
- Component
- Windows Ancillary Function Driver for WinSock
- Weakness
- CWE-416: Use After Free
- Issued by
- Microsoft
- Published
- 9 Jun 2026 · June 2026
- Last revised
- 9 Jun 2026
Updates that fix it
10 KBs| KB | Type | Restart | Applies to | Other CVEs |
|---|---|---|---|---|
| KB5093998 | Security Update | Required | Windows 11 Version 23H2 for ARM64-based Systems, Windows 11 Version 23H2 for x64-based Systems | All CVEs in KB5093998 |
| KB5094041 | Monthly Rollup | Required | Windows Server 2012 R2, Windows Server 2012 R2 (Server Core installation) | All CVEs in KB5094041 |
| KB5094042 | Monthly Rollup | Required | Windows Server 2012, Windows Server 2012 (Server Core installation) | All CVEs in KB5094042 |
| KB5094122 | Security Update | Required | Windows 10 Version 1607 for 32-bit Systems, Windows 10 Version 1607 for x64-based Systems, Windows Server 2016 and 1 more | All CVEs in KB5094122 |
| KB5094123 | Security Update | Required | Windows 10 Version 1809 for 32-bit Systems, Windows 10 Version 1809 for x64-based Systems, Windows Server 2019 and 1 more | All CVEs in KB5094123 |
| KB5094125 | Security Update | Required | Windows Server 2025, Windows Server 2025 (Server Core installation) | All CVEs in KB5094125 |
| KB5094126 | Security Update | Required | Windows 11 Version 24H2 for ARM64-based Systems, Windows 11 Version 24H2 for x64-based Systems, Windows 11 Version 25H2 for ARM64-based Systems and 1 more | All CVEs in KB5094126 |
| KB5094127 | Security Update | Required | Windows 10 Version 21H2 for 32-bit Systems, Windows 10 Version 21H2 for ARM64-based Systems, Windows 10 Version 21H2 for x64-based Systems and 3 more | All CVEs in KB5094127 |
| KB5094128 | Security Update | Required | Windows Server 2022, Windows Server 2022 (Server Core installation) | All CVEs in KB5094128 |
| KB5095051 | Security Update | Required | Windows 11 Version 26H1 for ARM64-based Systems, Windows 11 version 26H1 for x64-based Systems | All CVEs in KB5095051 |
Affected products
ESU, Windows30 affected products
- Windows 10 Version 1607 for 32-bit Systems
- Windows 10 Version 1607 for x64-based Systems
- Windows 10 Version 1809 for 32-bit Systems
- Windows 10 Version 1809 for x64-based Systems
- Windows 10 Version 21H2 for 32-bit Systems
- Windows 10 Version 21H2 for ARM64-based Systems
- Windows 10 Version 21H2 for x64-based Systems
- Windows 10 Version 22H2 for 32-bit Systems
- Windows 10 Version 22H2 for ARM64-based Systems
- Windows 10 Version 22H2 for x64-based Systems
- Windows 11 Version 23H2 for ARM64-based Systems
- Windows 11 Version 23H2 for x64-based Systems
- Windows 11 Version 24H2 for ARM64-based Systems
- Windows 11 Version 24H2 for x64-based Systems
- Windows 11 Version 25H2 for ARM64-based Systems
- Windows 11 Version 25H2 for x64-based Systems
- Windows 11 Version 26H1 for ARM64-based Systems
- Windows 11 version 26H1 for x64-based Systems
- Windows Server 2012
- Windows Server 2012 (Server Core installation)
- Windows Server 2012 R2
- Windows Server 2012 R2 (Server Core installation)
- Windows Server 2016
- Windows Server 2016 (Server Core installation)
- Windows Server 2019
- Windows Server 2019 (Server Core installation)
- Windows Server 2022
- Windows Server 2022 (Server Core installation)
- Windows Server 2025
- Windows Server 2025 (Server Core installation)