Out-of-bounds read in Microsoft products - CVE-2026-55122
Published: July 17, 2026
Vulnerability identifier: #VU138231
CSH Severity: Low
CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-55122
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to out-of-bounds read in Microsoft Office Excel when parsing a crafted Office file. A remote attacker can send a specially crafted file to a user and convince them to open it to disclose sensitive information.
The disclosed information may include small portions of heap memory. The Preview Pane is not an attack vector.
Affected software
Microsoft Office for macOS
Microsoft Excel
Office Online Server
Microsoft Excel
Office Online Server
How to mitigate CVE-2026-55122
Install security update from vendor's website.
Microsoft Office for macOS - update to 16.111.26071215
Microsoft Excel - update to 16.0.5561.1001
Office Online Server - update to 16.0.10417.20175
Microsoft Excel - update to 16.0.5561.1001
Office Online Server - update to 16.0.10417.20175