CVE-2026-21509
Microsoft Office Security Feature Bypass Vulnerability
Summary
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. Some of the impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.
Affected software
Vendor: Microsoft · Product: Office
Weakness types (CWE):
What to do
This vulnerability appears in CISA's Known Exploited Vulnerabilities catalog, meaning it is being exploited in the wild. Prioritize patching affected systems and verify exposure across your estate.
Related vulnerabilities in Microsoft
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| CVE-2021-34523 | Microsoft Exchange Server Privilege Escalation Vulnerability | 100.0% | Yes |
| CVE-2023-29357 | Microsoft SharePoint Server Privilege Escalation Vulnerability | 100.0% | Yes |
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