CVE-2022-24521: Windows CLFS Driver Out-of-Bounds Write Elevation of Privilege

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 17 September 2026. Confidence: medium.

high priorityIt is a locally exploitable privilege escalation with confirmed exploitation and ransomware use, though it requires an existing foothold rather than remote access.

What it is

The Windows Common Log File System (CLFS) driver contains an out-of-bounds write (CWE-787) that allows a local user to elevate privileges. Microsoft rates it 7.8 HIGH, and CISA added it to the Known Exploited Vulnerabilities catalog, so it is being used in real attacks. It affects a broad set of Windows client and server releases.

Impact

An attacker who already has a foothold on the host can gain SYSTEM-level code execution, giving full control of the machine. Because it is a privilege escalation, it is typically chained after initial access to deepen compromise.

Attack surface

The vector is local (AV:L) with low privileges required (PR:L) and no user interaction (UI:N), so the attacker must already be able to run code on the target. It is not remotely reachable on its own.

Exploitation

CISA KEV lists it as exploited, with known ransomware campaign use, and EPSS puts 30-day probability at about 7.1 percent (93.9th percentile). No public exploit details are given in the record.

What to do

• Apply the Microsoft security update for CVE-2022-24521 on all affected Windows client and server versions.
• Prioritize patching internet-facing and high-value hosts, and any system where untrusted users can run code.
• Restrict local logon and code execution rights to reduce the pool of accounts that can trigger the flaw.
• Monitor for and remove commodity malware or tooling that could chain this escalation, given the ransomware association.

Detection

• Alert on unexpected processes spawning with SYSTEM integrity from non-service parents, especially after user-level execution.
• Monitor CLFS-related file and registry activity in system paths for anomalous writes or handle access.
• Correlate local privilege escalation attempts with known post-exploitation and ransomware precursor behavior on the same host.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.