Microsoft has patched a critical flaw tagged as wormable and found to impact the latest desktop and server Windows versions, including Windows 11 and Windows Server 2022. The bug, tracked as CVE-2022-21907 and patched during this month’s patch Tuesday, was discovered in the HTTP Protocol Stack (HTTP.sys) used as a protocol listener for processing HTTP requests by the Windows Internet Information Services (IIS) web server. Successful exploitation requires threat actors to send maliciously crafted packets to targeted Windows servers, which use the vulnerable HTTP Protocol Stack for processing packets. Microsoft recommends users prioritize patching this flaw on all affected servers since it could allow unauthenticated attackers to remotely execute arbitrary code in low complexity attacks and in most situations without requiring user interaction. Luckily, the flaw is not currently under active exploitation and there are no publicly disclosed proof of concept exploits.