Off-by-one in Microsoft Office for macOS and Microsoft Office - CVE-2026-108443
Published: November 5, 2026
Vulnerability identifier: #VU159363
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-2026-108443
CWE-ID: CWE-193
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code in the victim user's context.
The vulnerability exists due to an off-by-one error in Microsoft Office Word when processing document numbering features. A remote attacker can send a specially crafted Word document and convince a user to open it and use Word's numbering features to execute arbitrary code in that user's context.
The Preview Pane is not an attack vector for this vulnerability.
Affected software
Microsoft Office for macOS
Microsoft Office
Microsoft Office
How to mitigate CVE-2026-108443
Install security update from vendor's website.
Microsoft Office for macOS - update to 16.114 26101123
Microsoft Office - addressed in versions 16.0.14334.20974, 16.0.17932.21056
Microsoft Office - addressed in versions 16.0.14334.20974, 16.0.17932.21056