According to Symantec the first exploitation of the vulnerability was discovered on 11.01.2009.
Vulnerable component: Microsoft Excel
CVSSv3 score: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
CWE-ID: CWE-190 - Integer Overflow or Wraparound
The vulnerability alows a remote attacker to execute arbitrary code on the target system.
The weakness exists due to integer overflow when parsing the Excel spreadsheet file format. A remote attacker can create a specially crafted Excel file containing a malformed object record, trick the victim into opening it, trigger memory corruption and execute arbitrary code on the target system with privileges of the current user.
Successful exploitation of the vulnerability results in arbitrary code execution on the vulnerable system.