Untrusted Pointer Dereference in Microsoft products - CVE-2026-55138
Published: July 17, 2026
Vulnerability identifier: #VU138214
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-2026-55138
CWE-ID: CWE-822
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 untrusted pointer dereference in Microsoft Office Excel when parsing a crafted Office file. A remote attacker can send a specially crafted file and convince the victim to open it to disclose sensitive information.
The disclosed data is limited to 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-2026-55138
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