#VU121289 Improper access control in Microsoft Office LTSC and Microsoft 365 Apps for Enterprise - CVE-2026-20949
Published: January 13, 2026
Vulnerability identifier: #VU121289
Vulnerability risk: High
CVSSv4.0: 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-2026-20949
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
Microsoft Office LTSC
Microsoft 365 Apps for Enterprise
Microsoft Office LTSC
Microsoft 365 Apps for Enterprise
Software vendor:
Microsoft
Microsoft
Description
The vulnerability allows a remote attacker to gain unauthorized access to otherwise restricted functionality.
The vulnerability exists due to improper access restrictions in Microsoft Excel. A remote attacker can trick a victim to open the malicious workbook, enable editing and then click the attacker‑supplied Quick Access Toolbar (QAT) button to bypass a security feature.
Remediation
Install updates from vendor's website.