Privilege Escalation in Microsoft Windows DWM Core Library (CVE-2025-30400)

Historical catalog analysis: CISA added this entry on May 13, 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-2025-30400 is a Use-After-Free (CWE-416) vulnerability located within the Microsoft Windows DWM Core Library. This flaw allows an attacker who already has authorized access to the system to elevate their privileges locally. On May 13, 2025, CISA added this vulnerability to its Known Exploited Vulnerabilities (KEV) catalog, indicating that it has been observed in active exploitation.

Exposure and applicability

This vulnerability affects systems running Microsoft Windows that utilize the DWM Core Library. Because the exploit requires an authorized attacker to be present on the system, the primary exposure path is local. This makes the flaw particularly relevant for environments where multiple users share a system or where initial access has already been gained through other means, as it provides a mechanism to move from a limited user context to a higher privilege level.

Remediation priorities

Based on its inclusion in the CISA KEV catalog, remediation should be prioritized. Our analysis suggests the following approach for vulnerability management teams:

1. Identify Affected Assets: Inventory all Windows endpoints and servers to determine where the DWM Core Library is active and vulnerable.
2. Apply Vendor Patches: Deploy the specific updates provided by Microsoft via the MSRC update guide. This is the primary method for closing the Use-After-Free flaw.
3. Cloud Service Alignment: For organizations utilizing cloud services, ensure that remediation aligns with BOD 22-01 guidance where applicable to ensure consistency across hybrid environments.
4. Decommissioning: In rare cases where mitigations are unavailable or cannot be applied to legacy systems, the source suggests discontinuing use of the product.

How to validate remediation

Verification must go beyond confirming a version number or a successful patch installation. To ensure exposure is actually reduced, defenders should:

• Verify Patch Application: Confirm that the specific security update addressing CVE-2025-30400 is present across all identified assets.
• Configuration Audit: Ensure that no legacy configurations are bypassing the updated library components.
• Privilege Analysis: While not a direct test of the flaw, auditing for unexpected privilege changes in local accounts can help identify if the vulnerability was exploited prior to patching.

Limits and open questions

A successful patch application reduces the likelihood of exploitation but does not eliminate all residual risk associated with local privilege escalation. It remains unknown whether this specific vulnerability has been utilized by known ransomware campaigns. Furthermore, while CISA has set a remediation deadline of June 3, 2025, for federal agencies, non-federal organizations must determine their own urgency based on their internal risk appetite and the confirmed exploited status of the flaw.

Source and editorial note

CVE-2025-30400: Microsoft Windows DWM Core Library Use-After-Free Vulnerability · Source date: May 13, 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: May 16, 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 15, 2026 at 00:12 UTC.

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