CVE-2021-42321

Microsoft Exchange Server Remote Code Execution Vulnerability

CVE-2021-42321 is fixed in 4 products on 1 platform, first by KB5007409, released November 9, 2021. It is being exploited: CISA added it to the Known Exploited Vulnerabilities catalog on November 17, 2021, with known ransomware use. Patch Radar priority: Patch now.

Patch nowCISA KEVKnown ransomware use

CVSS

8.8

Important

Exploitation

Exploited

Reported by the vendor

CISA KEV

Nov 17, 2021

Federal due date Dec 1, 2021. Known ransomware use

EPSS

0.9174

99th percentile

Where it's fixed

Product	Fix	Released
Microsoft
Microsoft Exchange Server 2016 Cumulative Update 21	KB5007409	Nov 9, 2021
Microsoft Exchange Server 2016 Cumulative Update 22	KB5007409	Nov 9, 2021
Microsoft Exchange Server 2019 Cumulative Update 10	KB5007409	Nov 9, 2021
Microsoft Exchange Server 2019 Cumulative Update 11	KB5007409	Nov 9, 2021

Details

Published
November 17, 2021
CISA required action
Apply updates per vendor instructions.
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42321

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