CVE-2021-27736 Explained : Impact and Mitigation

FusionAuth fusionauth-samlv2 before 0.5.4 is vulnerable to XXE attacks due to unsafe usage of javax.xml.parsers.DocumentBuilderFactory. Attackers can exploit this by forging AuthnRequest or LogoutRequest, leading to potential security breaches.

Understanding CVE-2021-27736

This CVE refers to a vulnerability in FusionAuth fusionauth-samlv2 before version 0.5.4, enabling XXE attacks through a specific method of processing XML documents.

What is CVE-2021-27736?

The CVE-2021-27736 vulnerability in FusionAuth fusionauth-samlv2 allows malicious actors to conduct XXE attacks by manipulating certain XML requests, ultimately risking the confidentiality and integrity of data.

The Impact of CVE-2021-27736

Exploitation of this vulnerability can result in unauthorized access to sensitive information, data manipulation, and potential security breaches for systems using the affected versions of FusionAuth fusionauth-samlv2.

Technical Details of CVE-2021-27736

The technical details of CVE-2021-27736 include:

Vulnerability Description

FusionAuth fusionauth-samlv2 before 0.5.4 is susceptible to XXE attacks when processing fabricated AuthnRequest or LogoutRequest due to the unsafe usage of javax.xml.parsers.DocumentBuilderFactory.

Affected Systems and Versions

All versions before FusionAuth fusionauth-samlv2 0.5.4 are impacted by this vulnerability.

Exploitation Mechanism

Attackers can exploit this vulnerability by crafting malicious XML payloads within AuthnRequest or LogoutRequest, triggering the XXE vulnerability.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-27736, consider the following:

Immediate Steps to Take

Update FusionAuth fusionauth-samlv2 to version 0.5.4 or later to eliminate the vulnerability.
Implement strict input validation mechanisms to sanitize XML requests and prevent malicious content injection.

Long-Term Security Practices

Regularly update and patch software components to address known vulnerabilities promptly.
Conduct security audits and assessments to identify and remediate potential security weaknesses.

Patching and Updates

Stay informed about security advisories and updates from FusionAuth and promptly apply patches to address vulnerabilities and enhance system security.