CVE-2026-20831
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk22th percentile - higher than 22% of all known CVEs
Summary
A time-of-check time-of-use (TOCTOU) race condition exists in the Windows Ancillary Function Driver for WinSock. This allows an authorized attacker to elevate privileges locally.
Risk Assessment
An authorized user could exploit a timing window to gain elevated privileges, potentially compromising network and system security.
Recommendation
Install the latest Windows security updates.
Other vulnerabilities in Windows Ancillary Function Driver for WinSock
See all- CVE-2026-34344High
The Windows Ancillary Function Driver for WinSock has a vulnerability related to resource access using an incompatible type ('type confusion'), allowing an authorized attacker to elevate privileges locally.
- CVE-2026-20810High
A vulnerability in the Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally. The issue involves freeing memory not on the heap.
- CVE-2026-68820HighActively exploited
Use-after-free in Windows Ancillary Function Driver for WinSock. An authorized attacker can elevate privileges locally.
- CVE-2026-20860High
A type confusion vulnerability in the Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
- CVE-2025-21418HighActively exploited
Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability.
- CVE-2024-38193HighActively exploited
A vulnerability in the Windows Ancillary Function Driver for WinSock allows for elevation of privilege on Windows systems. The NVD description does not provide technical details or required user interaction.
- CVE-2026-88149High
A double free vulnerability in the Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
- CVE-2026-83738High
Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
- CVE-2026-70245High
A type confusion in the Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
- CVE-2026-70237High
Use after free vulnerability in the Windows Ancillary Function Driver for WinSock. An authorized attacker can elevate privileges locally.
Original NVD description (English source)
Time-of-check time-of-use (toctou) race condition in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS