Windows UPnP Device Host Untrusted Pointer Dereference Vulnerability (CVE-2026-27920)

CVE-2026-27920 is a vulnerability affecting the Windows Universal Plug and Play (UPnP) Device Host. This vulnerability stems from an untrusted pointer dereference, which could allow an attacker with local access and authorization to escalate their privileges on the system. The vulnerability was published on April 14, 2026. An attacker who successfully exploits this vulnerability could gain higher-level access to the system potentially leading to complete system compromise. This privilege escalation could be leveraged to install programs, view, change, or delete data, or create new accounts with full user rights.

Attack Chain

1. An attacker gains initial local access to a Windows system.
2. The attacker identifies that the Windows UPnP Device Host service is running.
3. The attacker crafts a malicious request leveraging the UPnP service.
4. The malicious request triggers the untrusted pointer dereference in the UPnP Device Host.
5. This dereference allows the attacker to overwrite critical system memory.
6. The attacker overwrites memory with a payload designed to inject code into a privileged process.
7. The injected code executes with elevated privileges, such as SYSTEM.
8. The attacker now has the ability to perform actions with elevated permissions.

Impact

Successful exploitation of CVE-2026-27920 allows a local attacker to elevate their privileges to SYSTEM. This gives the attacker complete control over the affected system. The number of potential victims includes any Windows system with the UPnP Device Host enabled. The impact includes data exfiltration, malware installation, and complete system compromise, which can result in significant financial and reputational damage.

Recommendation

• Monitor for suspicious process creations originating from the svchost.exe process hosting the UPnP Device Host service to detect potential exploitation attempts.
• Apply the patch provided by Microsoft for CVE-2026-27920 to remediate the vulnerability.
• Enable process creation logging to capture command-line arguments for svchost.exe, which is required for the provided Sigma rule to function effectively.