CVE-2018-8378: Microsoft Excel Viewer

Medium severity, CVSS 5.5. EPSS: 8.2% chance of exploitation in the next 30 days.

An information disclosure vulnerability exists when Microsoft Office software reads out of bound memory due to an uninitialized variable, which could disclose the contents of memory, aka "Microsoft Office Information Disclosure Vulnerability." This affects Word, Microsoft SharePoint Server, Microsoft Office Word Viewer, Microsoft Excel Viewer, Microsoft SharePoint, Microsoft Office.

Affected products

• Microsoft Excel Viewer: version 2007 only
• Microsoft Office: version 2010 only; version 2013 only; version 2016 only
• Microsoft Office Compatibility Pack: affected versions not specified
• Microsoft Office Web Apps: version 2010 only; version 2013 only
• Microsoft Office Word Viewer: affected versions not specified
• Microsoft SharePoint Enterprise Server 2013: affected versions not specified
• Microsoft SharePoint Enterprise Server 2016: affected versions not specified
• Microsoft SharePoint Server: version 2013 only
• Microsoft Word Automation Services: affected versions not specified

Published 2018-08-15. Last modified 2026-06-17.