CVE-2026-20810 Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
An authorized local attacker can elevate privileges via a memory corruption flaw in the Windows Ancillary Function Driver for WinSock.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-20810?
CVE-2026-20810 is a high-severity memory corruption vulnerability in Microsoft Windows 10 1809, published on 13 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Free of memory not on the heap in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
Weakness: CWE-590
Which versions are affected by CVE-2026-20810?
It affects 4 products.
Products include Microsoft Windows 10 1809, Microsoft Windows 10 21h2, Microsoft Windows 10 22h2, Microsoft Windows Server 2019.
How do I fix CVE-2026-20810?
No fix has been published for CVE-2026-20810 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-20810 being exploited?
There is no known exploitation of CVE-2026-20810 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Windows 10 1809
- CVE-2024-29988 Microsoft SmartScreen Prompt Security Feature Bypass
- CVE-2024-21412 Microsoft Windows Internet Shortcut Files Security Feature Bypass
- CVE-2025-62221 Microsoft Windows Use After Free
- CVE-2025-30400 Microsoft Windows DWM Core Library Use-After-Free
- CVE-2024-21338 Microsoft Windows Kernel Exposed IOCTL with Insufficient Access Control
Sources
Also known as GHSA-c77x-pfg5-gxc3.