Windows AFD.sys EUVD-2026-35564

Attacker must already have local code execution on the target Windows host with at least low-privilege user rights (CVSS PR:L) - this is not remotely exploitable and cannot be triggered by an unauthenticated network attacker. No user interaction is required (UI:N) and attack complexity is low (AC:L), so once the attacker is on the box, exploitation is reliable against default Windows installations that ship AFD.sys (i.e., all supported Windows versions). The limiting factor is the local-access prerequisite, meaning this CVE is a post-compromise escalation primitive rather than an initial-access vulnerability.

The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) confirms this requires local access with low privileges and no user interaction, yielding high impact across CIA - classic LPE characteristics. EPSS data was not provided in the input, and the CVE is not listed in CISA KEV, so there is no confirmed evidence of active exploitation. However, AFD.sys vulnerabilities have a strong track record of being chained into post-exploitation toolchains (e.g., used after initial phishing or browser RCE), and the low attack complexity combined with kernel-level impact makes this a meaningful patch priority for any Windows endpoint fleet. The Microsoft-internal reporter and absence of public POC suggests targeted-research rather than widespread exploitation at this time.

An attacker who has already obtained a low-privileged foothold on a Windows host - for example via phishing, a compromised browser, or stolen user credentials - invokes a crafted sequence of Winsock IOCTLs that triggers the use-after-free in AFD.sys. By reclaiming the freed kernel object with attacker-controlled data, they corrupt a kernel pointer or token field and elevate to NT AUTHORITY\SYSTEM. No public exploit is identified at time of analysis, but AFD.sys LPE primitives are routinely incorporated into post-compromise toolkits.