Authenticated local privilege escalation via heap overflow

Heap-based buffer overflow in Windows SMB Client in Microsoft Windows 11 version 26H1 before 10.0.28000.2704 allows local users to gain elevated privileges. Microsoft has disclosed only that the flaw is a heap overflow in the SMB client; no public advisory, CVE record, or patch diff retrieved for CVE-2026-62799 identifies the vulnerable function or the specific SMB input that overruns memory. Exploitation requires local authenticated access with low privileges, and the published CVSS scope and impacts indicate compromise of the same Windows host rather than remote code execution across the network.