The SMB Server in various Windows operating systems contains a resource management flaw—missing reference to an active allocated resource—that allows an unauthorized attacker to trigger a denial of service over the network. The consequence is the local SMB service becomes unresponsive, effectively cutting off remote file sharing and associated network services. This weakness is categorized as CWE‑771 (Improper Resource Management).

Affected releases include Microsoft Windows 10 versions 1607, 1809, 21H2, 22H2, Windows 11 versions 23H2, 24H2, 25H2, 26H2, 26H1, Windows Server 2012 (including Core), 2012 R2, 2016, 2019, 2022, and 2025. All builds that run the SMB server component are vulnerable.

The CVSS base score of 7.5 indicates a high severity. No EPSS score is published, and the vulnerability is not listed in CISA's KEV catalog, so publicly available exploitation may be limited. Nevertheless, the flaw can be triggered by unauthenticated SMB traffic, meaning any host that exposes SMB to untrusted networks is at risk. Attackers would need to craft SMB packets that exercise the missing resource reference; this can be facilitated by readily available SMB exploitation tools.