Executive brief
A security vulnerability exists in the Windows Network File System (NFS), a component used to share files between computers over a network. An authorized user on the network could exploit this flaw to gain higher-level system permissions than they should have. This could allow an attacker to access restricted data, modify system settings, or disrupt operations.
Technical details
This vulnerability is characterized as a Time-of-Check Time-of-Use (TOCTOU) race condition (CWE-367) within the Windows Network File System (NFS) component, which may also lead to a Use-After-Free (CWE-416) condition. An attacker must be authenticated to the network and successfully win a timing race to exploit the flaw. If successful, the attacker can achieve elevated privileges on the target system. The attack vector is network-based with high complexity due to the race condition requirement. 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 24H2, 25H2, 26H1
- Microsoft Windows Server 2012 All editions including Server Core
Timeline
- 2026-07-14: disclosed
- 2026-07-14: advisory: Microsoft published the security update guide.