MS.Office.CVE-2026-21509.Security.Bypass

Description

This indicates an attack attempt to exploit a Security Feature Bypass Vulnerability in Microsoft Office.
This vulnerability is due to an error when the vulnerable software handles a maliciously crafted rtf file. A remote attacker could exploit this vulnerability by enticing a target user to open a crafted file. Successful exploitation could result in a bypass of security mechanisms on the vulnerable system.

Affected Products

Microsoft Office 2019 for 32-bit editions
Microsoft Office 2019 for 64-bit editions
Microsoft 365 Apps for Enterprise for 32-bit Systems
Microsoft 365 Apps for Enterprise for 64-bit Systems
Microsoft Office LTSC 2021 for 64-bit editions
Microsoft Office LTSC 2021 for 32-bit editions
Microsoft Office LTSC 2024 for 32-bit editions
Microsoft Office LTSC 2024 for 64-bit editions
Microsoft Office 2016 (32-bit edition)
Microsoft Office 2016 (64-bit edition)

Impact

System Compromise: Remote attackers can gain control of vulnerable systems.

Recommended Actions

Apply the most recent upgrade or patch from the vendor.
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509

References