CVE-2026-21511
Microsoft Outlook Spoofing Vulnerability
CVSS v3
7.5
HIGH
EPSS Score
3.8 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
none
SSVC status
Description
Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.
Technical details
- Published
- 2026-02-10
- Last Modified
- 2026-02-11
Frequently asked questions
What is CVE-2026-21511?
Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.
Is CVE-2026-21511 actively exploited?
Active exploitation of CVE-2026-21511 has not been confirmed. Its EPSS score was 3.8% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2026-21511?
CVE-2026-21511 has a CVSS v3 base score of 7.5 (HIGH severity).
Is CVE-2026-21511 affecting your environment?
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