Windows Kernel Elevation of Privilege Vulnerability

Successful exploitation allows elevation of privilege on a vulnerable Windows system. In practical terms, an attacker who has already achieved code execution or foothold on the target can use the flaw to obtain higher privileges in kernel context, facilitating full compromise of the affected host. The vulnerability was used in real-world intrusion activity, indicating operational value for post-compromise privilege escalation.

If immediate patching is not possible, reduce exposure by limiting opportunities for attackers to gain an initial foothold on Windows endpoints, restricting execution of untrusted code, minimizing local user access, and monitoring for signs of post-compromise privilege escalation activity. Because this is a kernel elevation of privilege flaw already used in active attacks, mitigation is only a temporary risk-reduction measure and does not replace installing the security update.

Apply Microsoft’s July 2021 security updates that address CVE-2021-33771. Organizations should deploy the vendor-provided corrective updates for affected Windows systems according to Microsoft guidance and prioritize remediation because the vulnerability was exploited in the wild before patch release.