Executive Summary

PAC4J is vulnerable to a Cross-Site Request Forgery (CSRF) attack where an attacker can create a malicious website that automatically submits a forged request with a token whose hash collides with the victim's legitimate CSRF token.

The attacker does not need to know the victim's actual CSRF token or its hash beforehand because collisions in the deterministic String.hashCode() function can be computed directly, reducing the token's security to 32 bits.

This vulnerability bypasses CSRF protection, allowing unauthorized actions such as profile updates, password changes, account linking, and other state-changing operations without the victim's consent.

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Impact Analysis

This vulnerability can allow attackers to perform unauthorized state-changing operations on behalf of a user without their consent.

• Attackers can update user profiles.
• Attackers can change user passwords.
• Attackers can link accounts.
• Any other operations that change the state of the user's account can be performed maliciously.

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Mitigation Strategies

To mitigate this vulnerability, you should upgrade PAC4J to version 5.7.10 or later, or version 6.4.1 or later, where the issue has been fixed.

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Compliance Impact

The vulnerability in PAC4J allows an attacker to bypass CSRF protection, enabling unauthorized state-changing operations such as profile updates, password changes, and account linking without the victim's consent.

Such unauthorized actions could lead to violations of data protection and privacy regulations like GDPR and HIPAA, as they compromise the integrity and security of user data and user consent mechanisms.

However, the provided information does not explicitly discuss the impact of this vulnerability on compliance with these standards.

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