CVE-2021-26858

Known Exploited

Microsoft Exchange Server Remote Code Execution Vulnerability

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

7.8

CVSS

Severity: High

CVSS 3.1 •

CVSS 2.0 •

EPSS 73.30% Top 5%

KEV Since

Vendor Advisory microsoft.com

Affected: Microsoft Microsoft Exchange Server 2019

Affected: Microsoft Microsoft Exchange Server 2013 Cumulative Update 22

Affected: Microsoft Microsoft Exchange Server 2019 Cumulative Update 2

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 13

Affected: Microsoft Microsoft Exchange Server 2013 Cumulative Update 23

Affected: Microsoft Microsoft Exchange Server 2019 Cumulative Update 3

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 14

Affected: Microsoft Microsoft Exchange Server 2019 Cumulative Update 4

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 15

Affected: Microsoft Microsoft Exchange Server 2019 Cumulative Update 5

Affected: Microsoft Microsoft Exchange Server 2019 Cumulative Update 6

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 16

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 17

Affected: Microsoft Microsoft Exchange Server 2019 Cumulative Update 7

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 18

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 19

Affected: Microsoft Microsoft Exchange Server 2019 Cumulative Update 8

Affected: Microsoft Microsoft Exchange Server 2013 Cumulative Update 21

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 12

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 8

Affected: Microsoft Microsoft Exchange Server 2019 Cumulative Update 1

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 9

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 10

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 11

References

Link	Tags
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26858	patch vendor advisory

Frequently Asked Questions

What is the severity of CVE-2021-26858?: CVE-2021-26858 has been scored as a high severity vulnerability.
How to fix CVE-2021-26858?: To fix CVE-2021-26858, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-26858 being actively exploited in the wild?: It is confirmed that CVE-2021-26858 is actively exploited. Be extra cautious if you are using vulnerable components. According to its EPSS score, there is a ~73% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-26858?: CVE-2021-26858 affects Microsoft Microsoft Exchange Server 2019, Microsoft Microsoft Exchange Server 2013 Cumulative Update 22, Microsoft Microsoft Exchange Server 2019 Cumulative Update 2, Microsoft Microsoft Exchange Server 2016 Cumulative Update 13, Microsoft Microsoft Exchange Server 2013 Cumulative Update 23, Microsoft Microsoft Exchange Server 2019 Cumulative Update 3, Microsoft Microsoft Exchange Server 2016 Cumulative Update 14, Microsoft Microsoft Exchange Server 2019 Cumulative Update 4, Microsoft Microsoft Exchange Server 2016 Cumulative Update 15, Microsoft Microsoft Exchange Server 2019 Cumulative Update 5, Microsoft Microsoft Exchange Server 2019 Cumulative Update 6, Microsoft Microsoft Exchange Server 2016 Cumulative Update 16, Microsoft Microsoft Exchange Server 2016 Cumulative Update 17, Microsoft Microsoft Exchange Server 2019 Cumulative Update 7, Microsoft Microsoft Exchange Server 2016 Cumulative Update 18, Microsoft Microsoft Exchange Server 2016 Cumulative Update 19, Microsoft Microsoft Exchange Server 2019 Cumulative Update 8, Microsoft Microsoft Exchange Server 2013 Cumulative Update 21, Microsoft Microsoft Exchange Server 2016 Cumulative Update 12, Microsoft Microsoft Exchange Server 2016 Cumulative Update 8, Microsoft Microsoft Exchange Server 2019 Cumulative Update 1, Microsoft Microsoft Exchange Server 2016 Cumulative Update 9, Microsoft Microsoft Exchange Server 2016 Cumulative Update 10, Microsoft Microsoft Exchange Server 2016 Cumulative Update 11.