CVE-2021-31207

Microsoft Exchange Server Security Feature Bypass Vulnerability

CVE-2021-31207 is fixed in 5 products on 1 platform, first by KB5003435, released May 11, 2021. It is being exploited: CISA added it to the Known Exploited Vulnerabilities catalog on November 3, 2021, with known ransomware use. Patch Radar priority: Patch now.

Patch nowCISA KEVKnown ransomware usePublicly disclosed

CVSS

6.6

Moderate

Exploitation

Exploited

Listed by CISA

CISA KEV

Nov 3, 2021

Federal due date Nov 17, 2021. Known ransomware use

EPSS

0.9978

99th percentile

Where it's fixed

Product	Fix	Released
Microsoft
Microsoft Exchange Server 2013 Cumulative Update 23	KB5003435	May 11, 2021
Microsoft Exchange Server 2016 Cumulative Update 19	KB5003435	May 11, 2021
Microsoft Exchange Server 2016 Cumulative Update 20	KB5003435	May 11, 2021
Microsoft Exchange Server 2019 Cumulative Update 8	KB5003435	May 11, 2021
Microsoft Exchange Server 2019 Cumulative Update 9	KB5003435	May 11, 2021

Details

Published
May 11, 2021
CISA required action
Apply updates per vendor instructions.
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-31207

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