Type Confusion in Microsoft products - CVE-2026-55024
Published: July 17, 2026
Vulnerability identifier: #VU138192
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2026-55024
CWE-ID: CWE-843
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 execute arbitrary code.
The vulnerability exists due to access of resource using incompatible type 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 execute arbitrary code.
The vulnerability may also allow disclosure of small portions of heap memory. User interaction is required to open the crafted file, and the Preview Pane is not an attack vector.
How to mitigate CVE-2026-55024
Install security update from vendor's website.