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CVE-2021-42321

8.8
HIGHCVSS v3.1 Base Score
93.62%
HIGH RiskEPSS (100th percentile)
KEV
NVD-CWE-Other

Microsoft Exchange Server Remote Code Execution Vulnerability

Published: 11/10/2021
Modified: 10/30/2025
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ACTIVELY EXPLOITED IN THE WILD

This vulnerability is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

Vulnerability Name:

Microsoft Exchange Server Remote Code Execution Vulnerability

Vendor / Product:

Microsoft Exchange

Required Action:

Apply updates per vendor instructions.

Due Date: 12/1/2021(OVERDUE)
Ransomware Campaign Use
Added to KEV:

11/17/2021

Notes:

https://nvd.nist.gov/vuln/detail/CVE-2021-42321

Vulnerability Summary

CVSS v3 Score

8.8HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v2 Score

6.5

AV:N/AC:L/Au:S/C:P/I:P/A:P

EPSS Score (Exploitation Probability)

93.62%HIGH Exploitation Risk
100th percentile

This vulnerability has a 93.62% probability of being exploited in the next 30 days, ranking higher than 100% of all scored CVEs.

CWE Classification

NVD-CWE-Other

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