CVE-2026-55054: Microsoft 365 Apps

Medium severity, CVSS 6.5. EPSS: 0.9% chance of exploitation in the next 30 days.

Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.

Affected products

• Microsoft 365 Apps: affected versions not specified
• Microsoft Excel: version 2016 only
• Microsoft Office: version 2019 only
• Microsoft Office 2021: before 16.111.26071215 (fixed in 16.111.26071215); affected versions not specified
• Microsoft Office 2024: before 16.111.26071215 (fixed in 16.111.26071215); affected versions not specified
• Microsoft Office 365: before 16.111.26071215 (fixed in 16.111.26071215)
• Microsoft Office Online Server: before 16.0.10417.20175 (fixed in 16.0.10417.20175)

Published 2026-07-14. Last modified 2026-07-15.