Heap-based buffer overflow in Microsoft products - CVE-2026-78526
Published: September 9, 2026
Vulnerability identifier: #VU148244
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-2026-78526
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 Word when processing a specially crafted Word document containing a malicious image. A remote attacker can send a specially crafted Word document to a target user to execute arbitrary code.
User interaction is required to open the document and apply the Artistic Cutout picture effect. The Preview Pane is not an attack vector.
Affected software
Microsoft Office for macOS
Microsoft 365 Apps for Enterprise
Microsoft Office
Microsoft 365 Apps for Enterprise
Microsoft Office
How to mitigate CVE-2026-78526
Install security update from vendor's website.
Microsoft Office for macOS - update to 16.112.26083020
Microsoft 365 Apps for Enterprise - update to 16.0.20326.20138
Microsoft Office - addressed in versions 16.0.5569.1002, 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976
Microsoft 365 Apps for Enterprise - update to 16.0.20326.20138
Microsoft Office - addressed in versions 16.0.5569.1002, 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976