Out-of-bounds write in Microsoft 365 Apps for Enterprise and Microsoft Office - CVE-2026-78524
Published: September 9, 2026
Vulnerability identifier: #VU148242
CSH Severity: High
CVSS v4: 8.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-78524
CWE-ID: CWE-787
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 an out-of-bounds write in Microsoft Office when processing a specially crafted file. A remote attacker can trick the victim into opening a specially crafted file to execute arbitrary code.
The Preview Pane is not an attack vector.
Affected software
Microsoft 365 Apps for Enterprise
Microsoft Office
Microsoft Office
How to mitigate CVE-2026-78524
Install security update from vendor's website.
Microsoft 365 Apps for Enterprise - update to 16.0.20326.20138
Microsoft Office - addressed in versions 16.0.5569.1000, 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976
Microsoft Office - addressed in versions 16.0.5569.1000, 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976