An integer underflow flaw in the Windows NT OS Kernel enables an authorized local user to gain elevated privileges. The flaw stems from a wrap or wraparound condition that allows the kernel to read or write memory outside intended bounds, leading to escalation of privileges and potential full system compromise.

The vulnerability affects multiple Windows releases: Windows 10 versions 1607, 1809, 21H2 and 22H2; Windows 11 versions 23H2, 24H2, 25H2, 26H1 (including arm64 and x64 builds); and Windows Server editions 2012, 2012 R2, 2016, 2019, 2022 and 2025 (including server core installations).

The CVSS score of 7.8 indicates a high severity issue. The EPSS score is not available, and the vulnerability is not listed in CISA’s KEV catalog, suggesting fewer observed exploits but still significant risk. An attacker with local or authorized access can exercise the flaw to elevate privileges. The likely attack vector requires a local privileged context, such as a standard user who can obtain temporary administrative rights or who can run local code.