Heap-based buffer overflow in Microsoft Office for macOS and Microsoft Office - CVE-2026-55129

Vulnerability details

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.

Affected software

How to mitigate CVE-2026-55129

External References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-55129
• https://www.microsoft.com/en-us/microsoft-365/mac/microsoft-365-for-mac?msockid=35f9adb0e74b61392038b90de6fe608c

Related Security Bulletins

• Multiple vulnerabilities in Microsoft Office