One of the more interesting recent Windows privilege escalation vulnerabilities is CVE-2026-42911 in afd.sys (the Ancillary Function Driver for WinSock) The bug was a use-after-free in the kernel-mode networking subsystem. By triggering the vulnerable code path and reclaiming the freed kernel object with controlled data, an attacker could cause the kernel to dereference a stale pointer and operate on attacker-controlled memory. This memory corruption primitive could be leveraged to gain arbitrary kernel code execution and ultimately elevate privileges from a low-privileged user account to SYSTEM. What makes the vulnerability notable is that afd.sys has historically been a rich source of kernel exploits, sitting directly on the boundary between user-mode socket APIs and kernel networking internals. Successful exploitation required only local code execution and no user interaction, making it an attractive post-compromise privilege escalation vector. Microsoft patched the flaw in the June 2026 security updates by correcting the underlying object lifetime management in the WinSock driver.
Post summary
The post announces a Windows kernel use‑after‑free in afd.sys that can be leveraged for local privilege escalation and notes that Microsoft released a patch in the June 2026 security updates.
