Microsoft's August Patch Tuesday Fixes 421 Flaws — Including One Under Active Attack

Microsoft has released its August 2026 Patch Tuesday updates, addressing a massive 421 vulnerabilities across its product line. Among these, one flaw stands out as particularly urgent: a zero-day vulnerability in the afd.sys Windows kernel-mode driver that is already being actively exploited in the wild.

The flaw is a 'use-after-free' bug, a type of software error where a program continues to use a piece of computer memory after it has been freed up, which attackers can exploit to trigger unpredictable behaviour. In this case, successful exploitation allows attackers to gain SYSTEM-level privileges, the highest level of access on a Windows machine. This means an attacker who has already gained a foothold on a device, even a low-privileged one, could use this flaw to take complete control of it, install further malware, or move deeper into a business's network.

Because this vulnerability is already being used by attackers, it poses an immediate risk to any business running unpatched Windows systems. With 421 fixes in total covering a wide range of Microsoft products, this is one of the largest Patch Tuesday releases in recent memory, underscoring the importance of a swift and thorough update process.