Improper access control in the Windows Event Logging Service can allow a local attacker that already has authorized access to elevate privileges to higher levels. The bug results from an access control failure (CWE‑284) that permits the attacker to gain additional Windows user rights or become a local administrator. The impact includes full control over the machine, the ability to install malicious software, modify system settings, and potentially move laterally within the local network.

Microsoft Windows 10 versions 1607, 1809, 21H2, and 22H2; Microsoft Windows 11 versions 23H2, 24H2, 25H2, 26H1, and 22H3; Microsoft Windows Server 2012, Server 2012 R2, Server 2016, Server 2019, Server 2022, Server 2025, and Server 23H2, including server core installations where noted. All affected builds are listed in the Microsoft Security Update Guide for CVE‑2026‑33834.

The CVSS score of 7.8 indicates a high severity for local privilege escalation. Exploitability data (EPSS) is not available, but the vulnerability is not listed in the CISA KEV catalog. The likely attack vector is local, requiring that the attacker already has an authorized account or is present on the machine. Once exploited, the attacker can gain elevated access to the Windows operating system.