The Function Discovery Service (fdwsd.dll) contains a race condition that occurs when multiple threads access a shared resource without proper synchronization. This flaw allows an attacker who already has local access to the system to gain higher privileges, enabling the execution of arbitrary code, modification of system settings, or installation of malicious software, thereby compromising confidentiality, integrity, and availability.

Microsoft Windows operating systems, including Windows 10 versions 1607, 1809, 21H2, and 22H2; Windows 11 versions 23H2, 24H2, 25H2, 22H3, and 26H1; and Windows Server editions 2012, 2012 R2, 2016, 2019, 2022, 2025, and 23H2, are susceptible. The vulnerability affects both standard and core installations where the Function Discovery Service is present.

The CVSS score of 7.0 indicates a medium‑to‑high severity risk, and while no EPSS score is available, the lack of a narrow public exploit suggests moderate likelihood of real‑world exploitation. Because the flaw requires local, authorized access, the threat surface is confined to insider or local compromise scenarios. Microsoft has issued a patch; following the update guide will remove the risk. The vulnerability is not yet listed in the CISA KEV catalog, so there is no immediate known widespread exploitation reported.