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Exploit / PoCcriticalExploited in the wild

Microsoft reveals actively exploited Office zero-day, provides emergency fix (CVE-2026-21509)

Help Net Securityby @zeljkazorz ()2 min read2 · 1 read
Analyze CVE-2026-21509 with Vani AIImpact, affected versions, exploitation, mitigations and detection

Vulnerabilities mentioned

All
CVEVulnerabilityCVSSEPSSSignalsPublished
CVE-2026-21509
Local Security Feature Bypass in Microsoft Office Under Active Exploitation
7.871%KEV
KEV

From the original article

2 min read at helpnetsecurity.com

Microsoft released emergency Office security updates to fix a security feature bypass vulnerability (CVE-2026-21509) that its threat intelligence and security teams spotted being exploited in the wild in zero-day attacks. Users and admins are advised to review the associated advisory and to implement updates or mitigations as soon as possible.

Help Net Security

By @zeljkazorz · helpnetsecurity.com

Read the full article at Help Net Security

A short excerpt; the article and its images belong to the publisher. Summary, key facts and assessment above are AI-written from the article and can be wrong.