CVE-2026-55128: Microsoft 365 Apps

High severity, CVSS 7.8. EPSS: 0.6% chance of exploitation in the next 30 days.

Use after free in Microsoft Office Word allows an unauthorized attacker to execute code locally.

Affected products

• Microsoft 365 Apps: affected versions not specified
• Microsoft Microsoft 365: affected versions not specified
• Microsoft Office 2019: affected versions not specified
• Microsoft Office 2021: affected versions not specified
• Microsoft Office 2024: affected versions not specified
• Microsoft Office Online Server: before 16.0.10417.20175 (fixed in 16.0.10417.20175)
• Microsoft SharePoint Server: before 16.0.19725.20434 (fixed in 16.0.19725.20434); version 2016 only; version 2019 only
• Microsoft Word: version 2016 only

Published 2026-07-14. Last modified 2026-07-16.