SB2026011372 - Multiple vulnerabilities in Microsoft Windows Ancillary Function Driver for WinSock

Description

This security bulletin contains information about 3 secuirty vulnerabilities.

1) Free of Memory not on the Heap (CVE-ID: CVE-2026-20810)

The vulnerability allows a local user to escalate privileges on the target system.

The vulnerability exists due to free of memory not on the heap issue in Windows Ancillary Function Driver for WinSock. A local user can gain elevated privileges on the system.

2) Type Confusion (CVE-ID: CVE-2026-20860)

The vulnerability allows a local user to escalate privileges on the target system.

The vulnerability exists due to a type confusion error in Windows Ancillary Function Driver for WinSock. A local user can gain elevated privileges on the system.

3) Time-of-check Time-of-use (TOCTOU) Race Condition (CVE-ID: CVE-2026-20831)

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a time-of-check, time-of-use (TOCTOU) race condition in Windows Ancillary Function Driver for WinSock. A local user can gain elevated privileges on the target system.

Remediation

Install update from vendor's website.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20810
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20860
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20831