CVE-2021-29456 Explained : Impact and Mitigation
Learn about CVE-2021-29456 affecting Authelia versions <= 4.27.4. Explore the impact, technical details, and mitigation steps to secure your systems.
Authelia allows open redirects on the logout endpoint.
Understanding CVE-2021-29456
This CVE affects Authelia versions <= 4.27.4, allowing attackers to redirect users from the web application to any domain using a HTTP query parameter on the logout endpoint.
What is CVE-2021-29456?
Authelia, an open-source authentication and authorization server, is impacted by CVE-2021-29456. Attackers can exploit this vulnerability to redirect users to potentially malicious sites.
The Impact of CVE-2021-29456
The vulnerability in Authelia versions <= 4.27.4 poses a medium risk with a base score of 5.7. While it does not directly impact the security of the web application itself, it can lead to open redirects.
Technical Details of CVE-2021-29456
In this section, we will delve into the vulnerability description, affected systems and versions, as well as the exploitation mechanism.
Vulnerability Description
The vulnerability allows attackers to redirect users from the web application to any domain, including potentially malicious sites, using a HTTP query parameter on the logout endpoint.
Affected Systems and Versions
Authelia versions <= 4.27.4 are affected by this vulnerability.
Exploitation Mechanism
Attackers exploit this vulnerability by manipulating a HTTP query parameter to redirect users from the web application to unauthorized domains.
Mitigation and Prevention
To mitigate the risks associated with CVE-2021-29456, users should take immediate steps, implement long-term security practices, and ensure timely patching and updates.
Immediate Steps to Take
Utilize a reverse proxy to strip the query parameter from the affected endpoint until the patch for version 4.28.0 is applied.
Long-Term Security Practices
Regularly update Authelia to the latest version, monitor security advisories, and reinforce security measures to prevent unauthorized redirects.
Patching and Updates
Apply the patch provided by Authelia for version 4.28.0 to address the vulnerability effectively.