CVE-2022-21919

The Windows User Profile Service contains a link-following flaw (CWE-59) that lets an authenticated local attacker with low privileges elevate to SYSTEM/administrator rights, typically by planting a junction or symlink that the service follows while handling user profile operations. The attack is local-only (AV:L) with high attack complexity and no user interaction required, so it cannot be exploited remotely or by unauthenticated users. Any environment running the affected Windows releases — Windows 7, 8.1, RT 8.1, Windows 10 versions 1507 through 21H2, Windows 11 21H2, and Windows Server 2008 per the CPE data — is exposed wherever standard users can execute code. Microsoft shipped the fix in its January 2022 Patch Tuesday release, and CISA added the CVE to the Known Exploited Vulnerabilities catalog on 2022-04-25, confirming exploitation in the wild. Ransomware association is not documented, and no public proof-of-concept is known; EPSS currently puts 30-day exploitation probability at 3.0% (86th percentile).

What to do: Apply Microsoft's January 2022 Patch Tuesday security updates (or any later cumulative/LC updates) to all affected Windows 7/8.1/10/11 clients, Windows RT 8.1 devices, and Windows Server 2008 systems, per CISA's required action. Windows 7/8.1/Server 2008 may require Extended Security Updates where mainstream support has ended. Prioritize hosts that expose interactive logon to untrusted or low-privilege users and verify patch compliance, given the KEV listing confirms active exploitation.