CVE-2021-26427 : Vulnerability Insights and Analysis
Critical CVE-2021-26427 affects Microsoft Exchange Server versions 2016 CU22, 2019 CU11, 2013 CU23, 2016 CU21, and 2019 CU10. Learn about the impact, mitigation, and prevention.
A critical Microsoft Exchange Server Remote Code Execution Vulnerability (CVE-2021-26427) was disclosed on October 12, 2021.
Understanding CVE-2021-26427
What is CVE-2021-26427?
CVE-2021-26427 is a Remote Code Execution vulnerability affecting Microsoft Exchange Server.
The Impact of CVE-2021-26427
This critical vulnerability can allow an attacker to execute arbitrary code remotely on the affected Exchange Servers, leading to a complete compromise of the system.
Technical Details of CVE-2021-26427
Vulnerability Description
The vulnerability allows unauthenticated attackers to execute commands on the underlying operating system with SYSTEM privileges.
Affected Systems and Versions
- Microsoft Exchange Server 2016 CU22 (Version 15.0.0 to 15.01.2375.012)
- Microsoft Exchange Server 2019 CU11 (Version 15.02.0 to 15.02.0986.009)
- Microsoft Exchange Server 2013 CU23 (Version 15.00.0 to 15.00.1497.024)
- Microsoft Exchange Server 2016 CU21 (Version 15.01.0 to 15.01.2308.015)
- Microsoft Exchange Server 2019 CU10 (Version 15.02.0 to 15.02.0922.014)
Exploitation Mechanism
The vulnerability arises due to improper validation of user-supplied input by the Exchange Server, allowing an attacker to craft requests to exploit this issue.
Mitigation and Prevention
Immediate Steps to Take
Organizations should immediately apply the latest security updates released by Microsoft to mitigate this vulnerability. Network level authentication can also help protect against potential exploit attempts.
Long-Term Security Practices
Regularly monitor security mailing lists and vendor advisories for patch updates and security alerts. Implement a comprehensive security policy and conduct regular security audits to identify and address vulnerabilities.
Patching and Updates
Ensure that your Microsoft Exchange Servers are updated with the latest cumulative updates provided by Microsoft. Regularly check for security updates and apply them promptly to ensure protection against known vulnerabilities.