Windows AFD.sys EUVD-2026-35560

Exploitation requires the attacker to already have authenticated local code execution on the target Windows host as a low-privileged user (PR:L, AV:L) and the ability to spawn multiple threads to win a kernel race condition (AC:H). The afd.sys driver must be loaded, which is the default on all standard Windows desktop and server installations, so no special feature toggle is needed. Limiting factors that reduce realistic risk: no remote or network-reachable trigger, no user-interaction-driven path (UI:N but still requires a local foothold), high attack complexity due to timing sensitivity which may cause inconsistent success and BSODs on failure, and exploitation difficulty is meaningfully increased on hosts where Virtualization-Based Security and HVCI are enabled.

The CVSS 7.0 base score reflects a credible but non-trivial threat: AV:L requires the attacker to already have code execution on the host, AC:H reflects the timing-dependent race that must be won, and PR:L means a standard authenticated user account is sufficient - no admin rights needed. Confidentiality, integrity, and availability impacts are all High because successful exploitation yields kernel-mode (SYSTEM) execution. EPSS data was not provided, and the vulnerability is not on CISA KEV, so there is no signal of mass exploitation; however, AFD.sys LPE bugs have historically been weaponized quickly by commodity malware and ransomware affiliates once a working POC appears. The Denial of Service tag is consistent with the race-condition primitive - even an unsuccessful exploitation attempt can BSOD the host. Treat this as a meaningful post-compromise escalation risk rather than an internet-facing emergency.

A standard domain user who has obtained interactive or remote-shell access to a Windows host (e.g., via phishing or stolen credentials) runs a small exploit binary that opens a Winsock socket and issues conflicting IOCTLs from multiple threads to race afd.sys into freeing and reusing a socket-related kernel object. After winning the race, the attacker pivots the use-after-free into a kernel write primitive that overwrites the process token, granting SYSTEM, and then disables EDR, dumps LSASS, or installs persistence. No public exploit identified at time of analysis, but historical afd.sys LPE bugs have been productised within weeks of patch release.