Executive brief
Microsoft Excel contains a stack-based buffer overflow vulnerability that allows an attacker with local access to execute arbitrary code with user privileges. Exploitation requires the attacker to craft a malicious Excel file and have it opened by a user, potentially leading to system compromise, data theft, or malware installation.
Technical details
A stack-based buffer overflow exists in Microsoft Excel's file parsing logic, allowing an attacker to write beyond the boundaries of a stack-allocated buffer. The vulnerability requires local code execution context and user interaction (opening a malicious .xls or related file format). An attacker can exploit this by crafting a specially formatted Excel document that triggers the overflow when processed, achieving arbitrary code execution in the context of the user running Excel. A patch is expected to be available through Microsoft Security Updates.
Affected products
- Microsoft Excel <UNKNOWN>
Timeline
- 2026-09-08: disclosed