Use-after-free in Microsoft Office - CVE-2026-100209
Published: October 13, 2026
Vulnerability identifier: #VU154233
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-2026-100209
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 opening a malicious Office file. A remote attacker can send a malicious Office file and convince the victim to open it to execute arbitrary code.
The Preview Pane is not an attack vector.
Affected software
Microsoft Office
How to mitigate CVE-2026-100209
Install security update from vendor's website.
Microsoft Office - update to 16.0.17932.21056