CVE-2026-21509: Microsoft Office Security Feature Bypass Vulnerability

#microsoft #office #cybersecurity #vulnerability

CVE ID

CVE-2026-21509

Vulnerability Name

Microsoft Office Security Feature Bypass Vulnerability

Project: Microsoft
Product: Office

Date

Date Added: 2026-01-26
Due Date: 2026-02-16

Description

Microsoft Office contains a security feature bypass vulnerability in which reliance on untrusted inputs in a security decision in Microsoft Office could allow an unauthorized attacker to bypass a security feature locally.

Known To Be Used in Ransomware Campaigns?

Unknown

Action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Additional Notes

Please adhere to Microsoft’s recommended guidelines to address this vulnerability. Implement all final mitigations provided by the vendor for Office 2021, and apply the interim corresponding mitigations for Office 2016 and Office 2019 until the final patch becomes available. For more information please see: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509 ; https://nvd.nist.gov/vuln/detail/CVE-2026-21509