CVE-2026-21509
HIGHCVSS v3
7.8
HIGH
EPSS Score
12.5%
exploit probability
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
Technical Details
- CVSS v3 Vector
- 3.1
- Published
- 1/26/2026
- Last Modified
- 2/11/2026
Frequently Asked Questions
What is CVE-2026-21509?
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
Is CVE-2026-21509 actively exploited?
Active exploitation of CVE-2026-21509 has not been confirmed. The EPSS score is 12.5%, indicating the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2026-21509?
CVE-2026-21509 has a CVSS v3 base score of 7.8 (HIGH severity), with vector string 3.1.
Is CVE-2026-21509 affecting your environment?
Use isMalicious to check if any of your IPs or domains are associated with this vulnerability's IOCs.