Vulnerability
Microsoft Windows Ancillary Function Driver for WinSock Heap-Based Buffer Overflow Vulnerability
Microsoft Windows Ancillary Function Driver for WinSock contains a heap-based buffer overflow vulnerability that allows for privilege escalation, enabling a local attacker to gain SYSTEM privileges.
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
CISA description: “Microsoft Windows Ancillary Function Driver for WinSock contains a heap-based buffer overflow vulnerability that allows for privilege escalation, enabling a local attacker to gain SYSTEM privileges.”
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HAbove the FIRST 'patch on a priority schedule' threshold.
No VEX statements published for CVE-2025-21418. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.
Active exploitation with total impact on essential/support systems