Man-in-the-Middle (MitM) attack in Exim - CVE-2021-38371

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Main Vulnerability Database Vulnerabilities #VU73857

Man-in-the-Middle (MitM) attack in Exim - CVE-2021-38371

Published: March 20, 2023


Vulnerability identifier: #VU73857
CSH Severity: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2021-38371
CWE-ID: CWE-300
Exploitation vector: Remote access
Exploit availability: No public exploit available
Vulnerable software:
Exim
Software vendor:
Exim

Description

The vulnerability allows a remote attacker to perform MitM attack.

The vulnerability exists due to the way Exim handles concurrent STARTTLS sessions when sending out emails. A malicious server can send a response to the *next* command within the existing STARTTLS sessions and force the Exim to treat this session as trusted.


Remediation

Install updates from vendor's website.

External links