Vulnerability Description
PAC4J is vulnerable to Cross-Site Request Forgery (CSRF). A malicious attacker can craft a specially designed website which, when visited by a user, will automatically submit a forged cross-site request with a token whose hash collides with the victim's legitimate CSRF token. Importantly, the attacker does not need to know the victim’s CSRF token or its hash prior to the attack. Collisions in the deterministic String.hashCode() function can be computed directly, reducing the effective token's security space to 32 bits. This bypasses CSRF protection, allowing profile updates, password changes, account linking, and any other state-changing operations to be performed without the victim's consent. This issue was fixed in PAC4J versions 5.7.10 and 6.4.1
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Pac4J | Pac4J | >= 5.0.0, < 5.7.10 |
Related Weaknesses (CWE)
References
- https://cert.pl/en/posts/2026/04/CVE-2026-40458/Third Party Advisory
- https://www.pac4j.org/blog/security-advisory-pac4j-core-and-ldap.htmlVendor Advisory
FAQ
What is CVE-2026-40458?
CVE-2026-40458 is a vulnerability with a CVSS score of 6.5 (MEDIUM). PAC4J is vulnerable to Cross-Site Request Forgery (CSRF). A malicious attacker can craft a specially designed website which, when visited by a user, will automatically submit a forged cross-site reque...
How severe is CVE-2026-40458?
CVE-2026-40458 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-40458?
Check the references section above for vendor advisories and patch information. Affected products include: Pac4J Pac4J.