This vulnerability allows remote attackers to execute arbitrary code on affected installations of Microsoft Excel. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the parsing of XLS files. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process.
Microsoft Excel XLS File Parsing Uninitialized Pointer Remote Code Execution Vulnerability
Description of the security update for Office 2013: October 13, 2020
Description of the security update for Office 2016: October 13, 2020
Security Updates for Microsoft Office Products C2R (October 2020)