Overview
What is CVE-2021-26855?
Microsoft Exchange Server Remote Code Execution Vulnerability
CVE intelligenceCISA KEVRansomware use
CVE-2021-26855
Microsoft Exchange Server Remote Code Execution Vulnerability
9.8CRITICALCVSS out of 10
What this means
Actively exploited
CISA lists CVE-2021-26855 in its Known Exploited Vulnerabilities catalog, which means exploitation has been observed. The entry applies to Microsoft Exchange Server.
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CISA KEVListedObserved exploitation
EPSS100.0%Estimated 30-day exploitation probability
Ransomware useReported by CISACISA KEV ransomware field
Threat actors1Source-linked actor relationships