Use of uninitialized resource in Microsoft Office for macOS and Microsoft Office - CVE-2026-55042
Published: July 17, 2026
Vulnerability identifier: #VU138240
CSH Severity: Low
CVSS v4.0: 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/E:U/U:Clear
CVE-ID: CVE-2026-55042
CWE-ID: CWE-908
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 disclose sensitive information.
The vulnerability exists due to use of an uninitialized resource in Microsoft Office when parsing a crafted Office file. A remote attacker can send a malicious Office file and convince the user to open it to disclose sensitive information.
The Preview Pane is an attack vector, and successful exploitation could allow reading small portions of heap memory.
How to mitigate CVE-2026-55042
Install security update from vendor's website.