CVE-2009-1134: Excel in 2007 Microsoft Office System SP1 and SP2; Microsoft Office Excel Viewer; and Microsoft Office Comp...

Security readout for executives and security teams

This is a Microsoft Excel file-parsing flaw from 2009. A malicious spreadsheet-style BIFF file could cause affected Office 2007-era components to run attacker-controlled code when opened. Business urgency depends on whether those legacy components are still present and able to open untrusted files. Exposure is most likely in environments still running the named Office 2007, Excel Viewer, or Compatibility Pack versions, especially where users can receive or open untrusted spreadsheet files. Treat as high priority only if affected legacy Microsoft Office components remain in use. If inventory confirms none are present, document the finding as not applicable and retain evidence. Mitigation focus: Apply Microsoft guidance and updates from MS09-021 for affected Office components.; Remove or isolate legacy Excel Viewer and Compatibility Pack installations where no longer required.; Restrict opening of untrusted spreadsheet files on systems with affected components..

Prepared

Jun 28, 2026, 10:45 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.