Use-after-free in Microsoft products - CVE-2026-55128
Published: July 17, 2026
Vulnerability identifier: #VU138238
CSH Severity: High
CVSS v4: 8.4 [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]
CVE-ID: CVE-2026-55128
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to use-after-free in Microsoft Word when parsing a crafted Office file. A remote attacker can send a specially crafted file and convince the victim to open it to execute arbitrary code.
User interaction is required to open a crafted file, and the Preview Pane is not an attack vector.
Affected software
Microsoft Office for macOS
Microsoft Word
Microsoft SharePoint Server
Microsoft Word
Microsoft SharePoint Server
How to mitigate CVE-2026-55128
Install security update from vendor's website.
Microsoft Office for macOS - update to 16.111.26071215
Microsoft Word - update to 16.0.5561.1000
Microsoft SharePoint Server - addressed in versions 16.0.5561.1001, 16.0.10417.20175, 16.0.19725.20434
Microsoft Word - update to 16.0.5561.1000
Microsoft SharePoint Server - addressed in versions 16.0.5561.1001, 16.0.10417.20175, 16.0.19725.20434