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EXPOSURES › CVE-2026-21509

CVE-2026-21509

HIGH ⌖ ON CISA KEV · EXPLOITED
DETAIL
SourceCISA-KEV · kev Published2026-01-26 Referencehttps://nvd.nist.gov/vuln/detail/CVE-2026-21509 ↗
⚡ RCE ⌖ EXPLOITED IN THE WILD SHAME 72/100 exploited-in-wildunpatched

Microsoft Office flaw exploited, users advised to transition to supported versions.

A critical security feature bypass vulnerability in Microsoft Office allowed unauthorized attackers to bypass security features locally. Users are advised to stop using affected, unsupported versions and transition to supported ones to prevent potential unauthorized access.

Shame score — Critical vulnerability actively exploited in the wild with no patch available for unsupported, end-of-life versions.

▸ RECOMMENDED ACTION  Actively exploited (CISA KEV) — remediate now, ahead of your normal patch cycle.

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. 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 FEDRAMP PRODUCTS · 4
PRODUCTSTATUS
Azure Commercial Cloud
Microsoft
Authorized
Azure Government (includes Dynamics 365)
Microsoft
Authorized
Microsoft Office 365 GCC High
Microsoft
In Process
Office 365 Multi-Tenant & Supporting Services
Microsoft
Authorized