On May 27, Microsoft unexpectedly released the out-of-band update KB5061977 for Windows 11 version 24H2. This emergency patch comes shortly after the regular Patch Tuesday.
The update raises the OS build to 26100.4066 and is intended for systems running Windows 11 24H2. Microsoft states that the patch fixes a security vulnerability that is being actively exploited. Details about the vulnerability remain scarce for now, likely to limit abuse. The rapid rollout indicates a serious risk, possibly a vulnerability related to remote code execution or privilege escalation.
KB5061977 is available via Windows Update, Windows Update for Business, WSUS, and as a manual download in the Microsoft Update Catalog. Organizations are advised to install the update with priority, especially on systems with public access or business-critical functions.
No new features
Although this update is primarily intended as a security measure, it also includes reliability improvements. Microsoft emphasizes that users should not expect any new features or visible changes.
For IT administrators, an out-of-band update means extra pressure: the update must be scheduled outside of regular maintenance windows, which can disrupt planned processes. Nevertheless, swift action is essential. According to security researchers, even a short delay in patching can lead to large-scale attacks.
The update is part of a broader trend in which Microsoft is increasingly intervening outside the monthly cycle. It illustrates the growing importance of a flexible and well-prepared patch policy. Organizations would be wise to use test environments, back up systems in advance, and monitor updates closely.