Windows DWM 0-Day Vulnerability Allows Attackers to Escalate Privileges

Microsoft has addressed a significant zero-day vulnerability in the Windows Desktop Window Manager (DWM) Core Library, identified as CVE-2025-30400. This flaw, which was actively exploited in the wild, allowed attackers to gain SYSTEM-level privileges on affected systems.

Disclosed during Microsoft’s May 2025 Patch Tuesday, CVE-2025-30400 is categorized as an “Elevation of Privilege” vulnerability. It arises from a “use-after-free” memory corruption issue within the DWM Core Library, which is a critical component of the Windows operating system.

This vulnerability, cataloged under CWE-416, permits an authorized attacker to execute code with SYSTEM privileges—the highest level of access available on Windows systems—by taking advantage of improper memory management within the DWM process.

According to Microsoft, the vulnerability can be exploited locally by an attacker who already has access to the target machine. Once successfully exploited, the attacker can bypass standard security boundaries, potentially enabling them to install malicious software, alter system settings, or access sensitive data without detection.

Exploitation and Impact

Microsoft confirmed that CVE-2025-30400 had been actively exploited prior to the release of a patch, marking it as a genuine zero-day threat. Although the vulnerability was not disclosed publicly before the patch was issued, evidence of its exploitation was detected in the wild, prompting Microsoft to advise immediate action from users and administrators.

“Use after free in Windows DWM allows an authorized attacker to elevate privileges locally,” Microsoft stated in its advisory. The discovery of this flaw was credited to the company’s Threat Intelligence Center, underscoring its ongoing commitment to monitoring and responding to emerging threats.

Attackers leveraging this vulnerability could gain SYSTEM privileges, granting them complete control over the compromised device. This level of access poses a significant risk, as it enables persistent and stealthy attacks that can evade traditional security measures.

The fix for CVE-2025-30400 was released on May 13, 2025, as part of a comprehensive security update addressing a total of 72 to 83 vulnerabilities, including five zero-days that were actively exploited. Microsoft classified the severity of this vulnerability as “Important” and assigned it a CVSS score of 7.8, indicating its considerable risk to both enterprise and consumer systems.

Security experts, along with Microsoft, strongly recommend that all Windows users and administrators apply the latest updates without delay to mitigate the risk of exploitation. Organizations are also encouraged to enable automatic updates and review their security policies to ensure the rapid deployment of critical patches.

The identification and resolution of CVE-2025-30400 illustrate the ongoing challenge of securing complex operating system components like Windows DWM. With attackers actively exploiting such vulnerabilities to gain SYSTEM privileges, timely patching and vigilant security practices are essential for safeguarding Windows environments against sophisticated threats.

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Windows DWM 0-Day Vulnerability Allows Attackers to Escalate Privileges