An integer overflow or wraparound bug in the Windows DWM Core Library permits a user who already has local access to gain higher privileges on the affected system. The flaw can be triggered by manipulated data that causes improper handling of size calculations, leading to a memory corruption condition. The resulting execution of privileged code can compromise confidentiality, integrity, and availability for the machine by allowing local attackers to elevate to system level.

Affected products include Microsoft Windows 11 versions 24H2, 25H2, and 26H1, as well as Microsoft Windows Server 2025 and the Server Core installation of that edition. The vulnerable components are active on both ARM64 and x64 architectures as indicated by the supplier's common platform enumeration data.

The vulnerability has a CVSS score of 7.8, indicating significant severity. An exploit would require a privileged attacker already present on the host, which limits the attack surface to local environments. No known public exploit exists and the security advisory does not list the vulnerability in CISA’s KEV catalog. The EPSS score is not available, so the probability of exploitation is uncertain, but the high severity and local nature recommend prompt application of the vendor’s fix.