Heap-based buffer overflow in Microsoft Office for macOS and Microsoft Office - CVE-2026-55129
Published: July 17, 2026
Vulnerability identifier: #VU138219
CSH Severity: High
CVSS v4.0: 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/E:U/U:Amber
CVE-ID: CVE-2026-55129
CWE-ID: CWE-122
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Microsoft
Affected software:
Microsoft Office for macOS
Microsoft Office
Microsoft Office for macOS
Microsoft Office
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to heap-based buffer overflow in Microsoft Office for macOS when parsing a crafted Office file. A remote attacker can send a specially crafted file to a user and convince them to open or preview it to execute arbitrary code.
User interaction is required, and the Preview Pane can be used as an attack vector.
How to mitigate CVE-2026-55129
Install security update from vendor's website.