CVE-2020-28021 Explained : Impact and Mitigation

Exim 4 before 4.94.2 has Improper Neutralization of Line Delimiters, allowing an authenticated remote SMTP client to execute remote code as root.

Understanding CVE-2020-28021

Exim 4 vulnerability with potential remote code execution.

What is CVE-2020-28021?

Exim 4 before version 4.94.2 is susceptible to newline character insertion by an authenticated remote SMTP client, leading to remote code execution.

The Impact of CVE-2020-28021

Allows an authenticated remote attacker to insert newline characters into a spool file
Leads to remote code execution as root via AUTH= in a MAIL FROM command

Technical Details of CVE-2020-28021

Exim 4 vulnerability details.

Vulnerability Description

Improper Neutralization of Line Delimiters in Exim 4 before 4.94.2
Authenticated remote SMTP client can insert newline characters into a spool file

Affected Systems and Versions

Product: Exim 4
Vendor: N/A
Versions affected: N/A

Exploitation Mechanism

Authenticated remote SMTP client exploits newline character insertion via AUTH= in a MAIL FROM command

Mitigation and Prevention

Protecting systems from CVE-2020-28021.

Immediate Steps to Take

Update Exim to version 4.94.2 or later
Monitor SMTP traffic for suspicious activities

Long-Term Security Practices

Implement strict SMTP authentication mechanisms
Regularly audit and patch mail servers

Patching and Updates

Apply patches and updates promptly to mitigate the vulnerability