CVE-2021-21439 : Exploit Details and Defense Strategies

A possible Denial of Service (DoS) attack can be executed through a specially crafted URL in the email body, impacting OTRS AG (OTRS) Community Edition and OTRS versions.

Understanding CVE-2021-21439

This CVE highlights a vulnerability that can result in a DoS attack, leading to high CPU usage and potential system instability.

What is CVE-2021-21439?

CVE-2021-21439 involves the exploitation of a specially designed URL within an email, posing a risk of a DoS attack within OTRS software versions.

The Impact of CVE-2021-21439

The vulnerability could compromise the performance and stability of affected systems, potentially causing service disruptions.

Technical Details of CVE-2021-21439

The following outlines the specifics of this CVE to help users understand the risks and implications better.

Vulnerability Description

The issue arises from a lack of proper validation of URLs within email bodies, allowing attackers to use specially crafted URLs to trigger a DoS condition.

Affected Systems and Versions

OTRS AG ((OTRS)) Community Edition 6.0.x (from version 6.0.1) and OTRS 7.0.x (up to version 7.0.26) and 8.0.x (up to version 8.0.13) are impacted by this vulnerability.

Exploitation Mechanism

By sending emails containing malicious URLs, threat actors can exploit this vulnerability to exhaust system resources and disrupt services.

Mitigation and Prevention

To address the CVE-2021-21439 vulnerability effectively, implement the following mitigation strategies.

Immediate Steps to Take

Users are advised to update their OTRS installations to version 8.0.14 or OTRS 7.0.27 promptly to mitigate the risk of a DoS attack.

Long-Term Security Practices

Regularly monitor for security updates and patches from OTRS AG to stay protected against emerging vulnerabilities.

Patching and Updates

Stay vigilant about installing the latest patches and updates released by OTRS to address security issues and maintain system integrity.