Windows CLFS Driver Use-After-Free (CVE-2025-29824)

Historical catalog analysis: CISA added this entry on April 08, 2025. The entry reflects catalog information retrieved on August 31, 2026, not a snapshot archived on the inclusion date. Check current vendor guidance before acting.

What the vulnerability is

CVE-2025-29824 is a Use-After-Free (CWE-416) vulnerability located within the Microsoft Windows Common Log File System (CLFS) driver. This flaw allows an attacker who already has authorized access to a system to elevate their privileges locally.

Exposure and applicability

This vulnerability affects systems running the Microsoft Windows Common Log File System driver. Because this is a local privilege escalation (LPE) flaw, it does not provide initial remote entry; rather, it is applicable in scenarios where an attacker has already established a foothold on the endpoint. The risk profile for this vulnerability is elevated due to confirmed use in ransomware campaigns, where LPE is often used to disable security software or access sensitive system-level data.

Remediation priorities

Based on the known exploitation by ransomware actors, we analyze the following prioritization and remediation path:

1. Immediate Patching: Priority should be given to endpoints with high-value data or those serving as jump boxes, as these are primary targets for privilege escalation after initial compromise.
2. Vendor Mitigation: Defenders should apply mitigations according to Microsoft’s official instructions.
3. Product Decommissioning: In environments where the CLFS driver is not required and vendor mitigations cannot be applied or verified, discontinuing use of the affected product is a necessary alternative to reduce exposure.

How to validate remediation

Verification must move beyond simple version checks to ensure the vulnerability is no longer exploitable in the specific environment. We recommend the following validation approach:

• Deployment Confirmation: Verify that the vendor-supplied update or mitigation has been successfully applied across all targeted assets via configuration management logs.
• Behavioral Validation: In a staged environment, security teams should verify that the specific driver behavior associated with the Use-After-Free condition is neutralized.
• Exposure Reduction Evidence: Confirm that the privilege escalation path is closed by attempting to trigger the vulnerability using authorized, safe testing frameworks in a non-production environment.

Limits and open questions

Applying a patch or mitigation reduces the likelihood of exploitation but does not eliminate all residual risk associated with the CLFS driver. It remains unknown if other undiscovered flaws exist within the same component that could be leveraged similarly. Furthermore, because this is an LPE vulnerability, the primary residual risk is the initial access vector; patching CVE-2025-29824 prevents the elevation of privileges but does not prevent the initial unauthorized entry into the system.

Source and editorial note

CVE-2025-29824: Microsoft Windows Common Log File System (CLFS) Driver Use-After-Free Vulnerability · Source date: April 08, 2025 · Retrieved August 31, 2026.

Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.

Archive date: April 11, 2025. The displayed post date is assigned three days after the source date to organize this retrospective archive; it does not mean this site published the analysis then. First published by this site: October 18, 2026 at 00:47 UTC.

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