CVE-2026-40369 - Windows Kernel Untrusted Pointer Dereference Privilege Escalation

CVE-2026-40369 is a privilege escalation vulnerability affecting the Windows Kernel. Disclosed on May 12, 2026, this vulnerability stems from an untrusted pointer dereference, potentially allowing an attacker with local access and authorized privileges to execute code with elevated permissions. This could lead to a complete compromise of the affected system. Successful exploitation would require an attacker to already have some level of access to the system.

Attack Chain

1. Attacker gains initial access to the system with standard user privileges.
2. Attacker crafts a malicious program to trigger the untrusted pointer dereference in the Windows Kernel.
3. The malicious program exploits CVE-2026-40369 to overwrite kernel memory.
4. The kernel attempts to dereference the attacker-controlled pointer.
5. Due to the untrusted nature of the pointer, the dereference operation accesses an arbitrary memory location.
6. Attacker redirects code execution to a shellcode injected into a memory region.
7. The shellcode elevates the attacker’s privileges to SYSTEM.

Impact

Successful exploitation of CVE-2026-40369 allows a local attacker to escalate their privileges to SYSTEM. This would give the attacker complete control over the compromised system, allowing them to install malware, steal sensitive data, or disrupt critical services. The vulnerability has a CVSS v3.1 score of 7.8, indicating a high severity.

Recommendation

• Apply the patch released by Microsoft to remediate CVE-2026-40369 as soon as possible. Reference: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40369
• Deploy the Sigma rule “Detect Potential CVE-2026-40369 Exploitation Attempt” to identify suspicious process creation events indicative of exploitation attempts.
• Monitor for unusual system calls or API calls that could be indicative of kernel-level exploitation.