CVE-2021-42321
HIGH severity · CVSS 8.8 · actively exploited (CISA KEV)
8.8CVSS HIGH ● exploited ⚠ ransomware
🔴 Actively exploited in the wild (CISA Known Exploited Vulnerabilities).
⚠ Known use in ransomware campaigns. Added to KEV 2021-11-17. US federal agencies must patch by 2021-12-01.
Summary
Microsoft Exchange Server Remote Code Execution Vulnerability
Impact & exploitability
Attack vectorNetwork
Attack complexityLow
Privileges requiredLow
User interactionNone
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
Exploit probability (EPSS)94%
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Affected products we track (1)
Recommendation
This vulnerability is being actively exploited in the wild — patch affected products urgently. Open any affected product above for its exact safe version.
Official patch: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42321 ↗
Additional information
- NVD record
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42321Patch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42321Patch
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-42321
- http://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.htmlAdvisory
- http://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.htmlAdvisory
- http://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.htmlAdvisory
- http://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.htmlAdvisory