Privilege escalation via missing ExecuteProxyUpdates authentication

Authentication bypass in Microsoft SharePoint Server before August 2026 updates allows remote authenticated users to gain elevated privileges. Microsoft has not published the exact code path, but the August 2026 SharePoint security updates disable the ExecuteProxyUpdates feature by default, indicating that a privileged proxy-update function accepted requests without enforcing its intended authentication check. Exploitation requires a valid account and network access to an on-premises SharePoint server, and the reviewed public records bound the impact to privilege escalation rather than direct code execution for this CVE.