Windows Ancillary Function Driver EUVD-2026-35723

Exploitation requires the attacker to already have local code execution with at least standard-user privileges on the target Windows host (AV:L, PR:L) and the ability to issue IOCTLs to the afd.sys driver - which is reachable by any process holding a socket handle in a default Windows installation. No user interaction is required (UI:N). The high attack complexity (AC:H) indicates a race condition or other timing-dependent precondition that the attacker must reliably win, which limits trivial mass exploitation but does not preclude weaponization. The scope is unchanged (S:U), so impact is confined to the local kernel/host. There is no network-reachable attack path - purely local post-compromise escalation.

The CVSS 7.0 score reflects high attack complexity (AC:H) combined with local vector (AV:L) and required low privileges (PR:L), but full CIA impact (C:H/I:H/A:H) on success - a profile typical of race-condition-based UAF kernel bugs. EPSS data was not provided in the input, and the CVE is not listed in CISA KEV, so no automated probability or active-exploitation signal is available. No public exploit has been identified at time of analysis, which is consistent with this being a Microsoft-reported vulnerability with a patch released through the standard update channel. Real-world risk is moderate-to-high in post-compromise scenarios: any attacker who already has code execution as a standard user on a Windows endpoint (via phishing, malware, or stolen credentials) would view this as a viable SYSTEM-escalation primitive, especially given afd.sys's reachability from sandboxed contexts.

An attacker first gains low-privileged code execution on a Windows host through phishing, a browser exploit, or compromised credentials. From that foothold, the attacker's payload repeatedly invokes specific WinSock IOCTLs against afd.sys to win the race condition that triggers the use-after-free, corrupting a kernel object to overwrite the process token and yielding SYSTEM-level execution. No public POC has been published at the time of analysis, but past afd.sys UAFs have been weaponized within weeks of disclosure.