CVE-2019-1214

CVE-2019-1214 is an elevation of privilege flaw in the Windows Common Log File System (CLFS) driver, which improperly handles objects in memory (CWE-119). It is triggered locally: an attacker who can already execute low-privileged code on a vulnerable Windows machine can induce the driver's faulty memory handling, without any user interaction. Successful exploitation escalates the attacker's privileges on the host, yielding high impact to confidentiality, integrity and availability (effectively kernel/SYSTEM-level access). Affected systems span essentially the entire mainstream Windows install base at the time: Windows 7, 8.1, RT 8.1, Windows 10 versions 1507 through 1903, and Windows Server versions 1803 and 1903. The flaw was patched in the September 2019 Patch Tuesday release, which Microsoft flagged as one of two privilege escalation bugs actively exploited in attacks, and it was added to CISA's Known Exploited Vulnerabilities catalog on 2021-11-03; no public PoC is known.

What to do: Apply Microsoft's September 2019 (or later) cumulative/monthly rollup security updates across all affected Windows 7, 8.1, RT 8.1, Windows 10 (1507–1903) and Windows Server 1803/1903 systems, using ESU updates for extended-support Windows 7/8.1 hosts. Since this is a local privilege escalation listed in CISA KEV, prioritize patching multi-user, internet-reachable hosts such as RDS/terminal servers and VDI where unprivileged users can run code. Verify the September 2019 update is installed and monitor for local privilege escalation activity.