CVE-2017-2790: When processing a record type of 0x3c from a Workbook stream from an Excel file (.xls), JustSystems Ichitar...

Security readout for executives and security teams

CVE-2017-2790 is a file-processing flaw in JustSystems Ichitaro involving malformed Excel .xls content. A user must open a crafted file, after which the application may run attacker-controlled code with the user’s privileges. Business risk is highest where Ichitaro is installed on workstations that receive external documents. Exposure is likely limited to endpoints running JustSystems Ichitaro or Ichitaro Office that can open untrusted .xls files, especially via email, web downloads, or document exchange. The provided affected version data is not specific. Treat as high priority where Ichitaro is deployed and users handle external documents. Prioritize inventory, vendor guidance review, and document-handling controls. If Ichitaro is not present, exposure is likely low, but that should be validated through software inventory. Mitigation focus: Inventory endpoints for JustSystems Ichitaro or Ichitaro Office installations.; Check JustSystems and Talos guidance for affected versions and available updates.; Restrict or sandbox untrusted .xls files for Ichitaro users..

Prepared

May 23, 2026, 08:33 UTC (UTC+00:00)

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