Use after free in the Windows kernel gives an authenticated local user a path to gain kernel‑mode privileges. The vulnerability allows the attacker to execute arbitrary code with full system rights, potentially compromising integrity and confidentiality of the entire machine. The weakness is classified as a use‑after‑free error (CWE‑416).

Affected are Microsoft Windows 11 releases 23H2, 24H2, 25H2, 26H2 for both x64 and arm64 architectures, as well as Windows Server 2025 including the Server Core installation. These versions are listed in the Microsoft Security Update Guide for CVE‑2026‑83796.

The vulnerability has a CVSS score of 7.8, indicating a high impact if exploited. The EPSS score is not published, and the issue is not listed in the CISA KEV catalog. Exploitation requires an authorized local user; an attacker needs to execute code on the target machine, trigger the kernel use‑after‑free, and then obtain kernel‑mode execution. Because the data for EPSS is missing, the likelihood cannot be precisely quantified, but the high severity and local privilege escalation potential make it a significant risk for any compromised or trusted user.