CVE-2021-44878 : Security Advisory and Response

A vulnerability in pac4j versions prior to v5.3.0 allows for bypassing token validation when an OpenID Connect provider supports the "none" algorithm.

Understanding CVE-2021-44878

This CVE describes a security issue in pac4j that could lead to a malicious actor circumventing token validation through a specific algorithm.

What is CVE-2021-44878?

If an OpenID Connect provider allows tokens with no signature using the "none" algorithm, pac4j v5.3.0 and earlier do not reject it, enabling a potential attacker to inject a malformed ID token.

The Impact of CVE-2021-44878

The vulnerability permits an attacker to bypass token validation by exploiting the lack of signature verification for ID tokens, compromising security by inserting forged tokens.

Technical Details of CVE-2021-44878

This section outlines the technical specifics of the vulnerability in pac4j.

Vulnerability Description

An explanation of how pac4j versions prior to v5.3.0 can be manipulated to accept unverified ID tokens due to the "none" algorithm support.

Affected Systems and Versions

Affected Systems: All versions of pac4j prior to v5.3.0
Affected Products: Not applicable
Vendor: Not applicable

Exploitation Mechanism

The attacker can exploit the flaw by inserting a specially crafted ID token with the "none" algorithm value in the header, skipping signature validation.

Mitigation and Prevention

Steps to address and prevent the CVE-2021-44878 vulnerability.

Immediate Steps to Take

Upgrade affected pac4j instances to version 5.3.0 or later
Configure the OpenID Connect provider to disallow the "none" algorithm for token signatures

Long-Term Security Practices

Implement strict input validation and sanitization in your codebase
Regularly monitor security advisories for pac4j and OpenID Connect providers

Patching and Updates

Stay informed about security patches and updates for pac4j to address vulnerabilities promptly.