Heap-based buffer overflow in Microsoft Office for macOS and Microsoft Office - CVE-2026-55056
Published: July 17, 2026
Vulnerability identifier: #VU138235
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-2026-55056
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 heap-based buffer overflow in Microsoft Office when parsing a crafted Office file. A remote attacker can send a specially crafted file to a victim to execute arbitrary code.
User interaction is required to open or preview the crafted file, and the Preview Pane can be used as an attack vector.
Affected software
Microsoft Office for macOS
Microsoft Office
Microsoft Office
How to mitigate CVE-2026-55056
Install security update from vendor's website.
Microsoft Office for macOS - update to 16.111.26071215
Microsoft Office - update to 16.0.5561.1000
Microsoft Office - update to 16.0.5561.1000