Use-after-free in Office Online Server and Microsoft Office - CVE-2026-100212
Published: October 13, 2026
Vulnerability identifier: #VU154236
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-2026-100212
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 Office Excel when processing a malicious Office file. A remote attacker can send a malicious Office file to a user and convince them to open it to execute arbitrary code.
The Preview Pane is not an attack vector for this vulnerability.
Affected software
Office Online Server
Microsoft Office
Microsoft Office
How to mitigate CVE-2026-100212
Install security update from vendor's website.
Office Online Server - update to 16.0.10417.20228
Microsoft Office - addressed in versions 16.0.14334.20974, 16.0.17932.21056
Microsoft Office - addressed in versions 16.0.14334.20974, 16.0.17932.21056