CVE-2026-42896 – Windows DWM Core Library Elevation of Privilege Vulnerability

An elevation of privilege vulnerability exists in Windows DWM Core Library due to an integer overflow or wraparound issue, with heap-based buffer overflow also listed in the weakness details. An authorized local attacker could exploit this vulnerability to gain SYSTEM privileges. Microsoft has released an official fix, and no active exploitation has been reported.

CVSS Score: 7.8

SEVERITY: Important

THREAT:
This vulnerability allows a local attacker with low privileges to escalate access to SYSTEM. That level of access can enable full control of the affected device, including security bypass, credential theft, malware deployment, and system manipulation.

EXPLOITS:
No public exploit or proof-of-concept (PoC) exploit code has been confirmed. The vulnerability is not reported as exploited, and exploitation is assessed as less likely. Exploit code maturity is listed as Unproven.

TECHNICAL SUMMARY:
The vulnerability is caused by an integer overflow or wraparound in Windows DWM Core Library. The weakness details also identify CWE-122: Heap-based Buffer Overflow. A local authorized attacker could abuse the memory handling issue to elevate privileges. The CVSS vector shows local attack access, low attack complexity, low privileges required, no user interaction, unchanged scope, and high impact to confidentiality, integrity, and availability.

EXPLOITABILITY:
Affected software is Windows DWM Core Library on vulnerable Windows systems. Exploitation requires local access and low privileges, but no user interaction. Successful exploitation could grant SYSTEM privileges.

BUSINESS IMPACT:
This vulnerability is dangerous because it can help attackers expand control after initial compromise. SYSTEM privileges can allow attackers to disable defenses, access sensitive files, dump credentials, install persistence, and move deeper into enterprise environments.

WORKAROUND:
Apply the official Microsoft security update. If patching is delayed, restrict local access, limit low-privileged account permissions, monitor for unusual privilege escalation activity, and review endpoint security alerts involving DWM components.