An integer underflow flaw in the Windows File History Service lets a local user with sufficient access rights gain higher privileges on the affected system. The underflow, also known as wraparound, can corrupt internal counters that control access checks, enabling the attacker to bypass permission restrictions. Because the vulnerability operates entirely within privileged service code, the attacker can potentially gain system level rights after exploitation, compromising confidentiality, integrity, and availability of the local machine.

The flaw affects a broad range of Microsoft Windows operating systems. Specifically, Windows 10 releases 1607, 1809, 21H2, and 22H2; Windows 11 releases 23H2, 24H2, 25H2, 26H1; and Windows Server 2016 and 2019, including server core installations.

The CVSS score of 6.4 indicates a medium severity vulnerability. No EPSS score is available, and the issue is not listed in the CISA KEV catalog, suggesting a lower public exploitation probability at present. The attack vector is local and requires the attacker to be authorized on the target machine. If an attacker can exploit the service, they can elevate their privileges to a level that permits full control of the system. Given the moderate severity and local nature, organizations should treat this as a medium risk that warrants timely remediation.