Heap-based buffer overflow in Microsoft 365 Apps for Enterprise and Microsoft Office - CVE-2026-77898
Published: September 9, 2026
Vulnerability identifier: #VU148196
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-77898
CWE-ID: CWE-122
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to a heap-based buffer overflow in Microsoft Office when processing a crafted Office document. A remote attacker can send a specially crafted Office document to execute arbitrary code.
The Preview Pane is an attack vector.
Affected software
Microsoft 365 Apps for Enterprise
Microsoft Office
Microsoft Office
How to mitigate CVE-2026-77898
Install security update from vendor's website.
Microsoft 365 Apps for Enterprise - update to 16.0.20326.20138
Microsoft Office - addressed in versions 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976
Microsoft Office - addressed in versions 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976