Out-of-bounds read in Microsoft products - CVE-2026-55054
Published: July 17, 2026
Vulnerability identifier: #VU138224
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-55054
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Microsoft
Affected software:
Microsoft Office for macOS
Microsoft Excel
Office Online Server
Microsoft Office for macOS
Microsoft Excel
Office Online Server
Detailed vulnerability description
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 malicious Office file and convince the user to open it to disclose sensitive information.
User interaction is required to open the crafted file, and the Preview Pane is not an attack vector.
How to mitigate CVE-2026-55054
Install security update from vendor's website.