CVE-2021-26858

Microsoft Exchange Server Remote Code Execution Vulnerability

CVE-2021-26858 is fixed in 24 products on 1 platform, first by KB5000871, released March 10, 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 use

CVSS

7.8

Important

Exploitation

Exploited

Reported by the vendor

CISA KEV

Nov 3, 2021

Federal due date May 3, 2022. Known ransomware use

EPSS

0.9365

99th percentile

Where it's fixed

Product	Fix	Released
Microsoft
Microsoft Exchange Server 2013 Cumulative Update 21	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2013 Cumulative Update 22	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2013 Cumulative Update 23	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 10	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 11	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 12	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 13	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 14	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 15	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 16	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 17	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 18	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 19	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 8	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2016 Cumulative Update 9	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2019	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2019 Cumulative Update 1	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2019 Cumulative Update 2	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2019 Cumulative Update 3	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2019 Cumulative Update 4	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2019 Cumulative Update 5	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2019 Cumulative Update 6	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2019 Cumulative Update 7	KB5000871	Mar 10, 2021
Microsoft Exchange Server 2019 Cumulative Update 8	KB5000871	Mar 10, 2021

Details

Published
March 10, 2021
CISA required action
Apply updates per vendor instructions.
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26858

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