CVE-2025-33073

SMB is how Windows devices share files and communicate over a local network (and sometimes beyond, depending on your setup). This vulnerability lets a network attacker who already has “authorized” access punch through Windows permissions and gain higher privileges than they should. Think of it like someone getting into a building with a valid badge, then finding a flaw to turn that badge into full keys.

This matters if you run Microsoft Windows SMB Client on any of these systems: Windows Server 2008, 2012, 2012 R2, 2008 R2, 2016, 2019, 2022, or 2025, and Windows 10 or Windows 11. If an attacker has authorized network access to the network path where SMB traffic can reach the machine, they may be able to elevate privileges without needing you to do anything. The risk is tied to whether the attacker can reach SMB over the network in your environment (and whether they can already access the network in an authorized way).

This is RED because CISA listed CVE-2025-33073 in its KEV catalog, meaning real-world exploitation is considered credible enough to warrant government action. If your business relies on Windows file sharing or SMB connectivity, you should patch or mitigate immediately rather than waiting for additional reports.