CVE-2026-77898: Microsoft 365 Apps

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code over a network.

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

Published 2026-09-08. Last modified 2026-09-17.