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CVE-2021-42321: Microsoft Exchange Server Remote Code Execution Vulnerability
Microsoft Exchange · in CISA KEV since 2021-11-17
2021-11-17added to KEV
2021-12-01federal remediation due date
91.74%EPSS exploit probability (30 days) 99.8th percentile
8.8 HIGHCVSS 3.1
Knownknown ransomware use
7days from NVD publication to KEV
What it is
An authenticated attacker could leverage improper validation in cmdlet arguments within Microsoft Exchange and perform remote code execution.
Required action (CISA)
Apply updates per vendor instructions.
| CWE | CWE-184;CWE-502 |
|---|---|
| CVSS vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVD published | 2021-11-10 (Analyzed) |
Original records: NVD · CISA KEV · JSON: /api/cve/CVE-2021-42321.json · all KEV CVEs
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Get the full file: Exploited Vulnerabilities Brief – September 2026 ($29): this month's KEV additions ranked by EPSS, ransomware use and due date, ready to hand to a patch team. Checkout by Polar.