Worrying Microsoft Office security flaw patched - update now or risk hackers accessing your files

Microsoft Office.

• Microsoft issues emergency patch for Office zero-day CVE-2026-21509
• Vulnerability allows attackers to bypass OLE mitigations and execute malware
• CISA adds flaw to KEV catalog; exploitation details remain undisclosed

Microsoft has issued an emergency patch to fix a high-severity Office vulnerability that is being exploited in the wild as a zero-day.