Executive brief
A security vulnerability exists in the Windows SMB Server, which is the component responsible for sharing files and printers across a network. An authorized user on the network could exploit a timing-related flaw to gain higher-level system permissions than they should have. This could allow an attacker to access restricted data or perform unauthorized administrative actions across the corporate network.
Technical details
A race condition (CWE-362) exists in the Windows SMB Server due to improper synchronization when multiple threads access a shared resource. An attacker with low-privileged network credentials can exploit this vulnerability by sending specially crafted requests to trigger the synchronization flaw. Successful exploitation allows the attacker to elevate their privileges to a higher level, potentially gaining full administrative control over the affected system. The attack requires a network connection and valid authentication, but the complexity is rated as high due to the timing requirements inherent in race conditions. Microsoft has released security updates to address this issue across affected Windows and Windows Server versions.
Affected products
- Microsoft Windows 10 1607, 1809, 21H2, 22H2
- Microsoft Windows 11 22H3, 23H2, 24H2, 25H2
- Microsoft Windows Server 2012 All editions
- Microsoft Windows Server 2016 All editions
- Microsoft Windows Server 2019 All editions
- Microsoft Windows Server 2022 All editions
Timeline
- 2026-01-13: disclosed
- 2026-01-13: patched