Stack-based buffer overflow in Microsoft Office for macOS and Microsoft Office - CVE-2026-109505
Published: November 10, 2026
Vulnerability identifier: #VU164756
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-2026-109505
CWE-ID: CWE-121
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code with the victim user's permissions.
The vulnerability exists due to a stack-based buffer overflow in Microsoft Office Word when processing a specially crafted document. A remote attacker can supply a crafted Word document and convince a user to open it, start recording a macro, and apply a style supplied by the document to execute arbitrary code with the user's permissions.
The Preview Pane is not an attack vector.
Affected software
Microsoft Office for macOS
Microsoft Office
Microsoft Office
How to mitigate CVE-2026-109505
Install security update from vendor's website.
Microsoft Office for macOS - update to 16.115.26110837
Microsoft Office - addressed in versions 16.0.14334.21048, 16.0.17932.21140
Microsoft Office - addressed in versions 16.0.14334.21048, 16.0.17932.21140