Microsoft just fixed a significant security hole that hackers were already using to target Windows users. The vulnerability, tracked as CVE-2026-20805, affects the Desktop Window Manager (DWM), which is the part of Windows that handles how windows are rendered and displayed on your screen. While it is classified as an “information disclosure” flaw, the reality is more dangerous. It allows low-level attackers to peek into sensitive system memory, which they can then use to bypass other security protections and gain full control over a computer.
The scary part is that this was a zero-day exploit, meaning it was known and used by attackers before Microsoft had a chance to build a fix. According to Microsoft’s threat intelligence teams, the flaw was being used in real-world attacks, likely as part of a chain of exploits to break into secure systems. By leaking specific memory addresses, hackers can figure out exactly where critical security components are located, making it much easier to launch more damaging malware or steal private data. Because it does not require any interaction from the user—like clicking a link or opening a file—it is a highly effective tool for stealthy attacks.
The patch was included in the January 2026 Patch Tuesday update. It specifically targets older versions of Windows that are still in extended support, including Windows 10 v1809 and several versions of Windows Server. Even though these are legacy systems, many businesses and organizations still rely on them, making them prime targets for this kind of local privilege escalation. If you are running an older build of Windows for work or at home, you are at risk until the latest security update is installed.
You should check for Windows Updates immediately to make sure your system is protected. Most users will get the fix automatically through the standard update process, but system administrators should prioritize deploying KB5073723 or the relevant update for their specific server version. Since there is no simple workaround to block this exploit without the patch, keeping your software up to date is the only reliable way to stop attackers from using this memory leak against you.
