Code execution via crafted workbook parsing

Heap-based buffer overflow in Microsoft Office Excel allows attackers to execute code via a crafted workbook opened locally. Microsoft has disclosed only the bug class; public records do not identify the specific Excel parser, record type, or bounds check failure that overruns heap memory while processing untrusted workbook data. Exploitation requires user interaction with attacker-supplied content and yields code execution in the context of the user running Excel; no reviewed authoritative record reports active exploitation.