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CVE-2026-21509 is a high severity vulnerability with a CVSS score of 7.8. Exploits are available; patches have been released and should be applied urgently. This is classified as a zero-day vulnerability.
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Very high probability of exploitation in the next 30 days
EPSS predicts the probability of exploitation in the next 30 days based on real-world threat data, complementing CVSS severity scores with actual risk assessment.
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.
| Vendor | Product |
|---|---|
| Microsoft | Office |
| Microsoft | 365 Apps |
| Microsoft | Office Long Term Servicing Channel |