High severity · published Nov 10, 2021
CVE-2021-42321
Microsoft Exchange Server Remote Code Execution Vulnerability
RansomwareIn wildKEV
8.8
CVSS
91.7%
EPSS
Yes
On KEV
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)91.7% · higher than 100% of CVEs
Exploited in the wildYes
CISA KEVListed Nov 17, 2021
Federal remediation dueDec 1, 2021
Ransomware campaign useKnown
Affected products
Which versions
ES
Exchange Server · Microsoft
2016; 2016; 2019; 2019 · source: NVD, KEV
ME
Microsoft Exchange Server 2016 Cumulative Update 21 · Microsoft
15.01.0 before 15.01.2308.020 · source: vendor
ME
Microsoft Exchange Server 2016 Cumulative Update 22 · Microsoft
15.0.0 before 15.01.2375.017 · source: vendor
ME
Microsoft Exchange Server 2019 Cumulative Update 10 · Microsoft
15.02.0 before 15.02.0792.019 · source: vendor
ME
Microsoft Exchange Server 2019 Cumulative Update 11 · Microsoft
15.02.0 before 15.02.0986.014 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-42321
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-42321
CISA KEV catalogue
https://www.cisa.gov/known-exploited-vulnerabilities-catalog
vendor-advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42321
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