Vulnerability · Published Apr 17, 2026 · Assigned by CERT-PL
CVE-2026-40458Cross-Site Request Forgery in PAC4J
High 7.0
In plain English
A high-severity cross-site request forgery in PAC4J from PAC4J. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Maven | org.pac4j:pac4j-core | 5.7.10 | GHSA-xw5c-jc7x-gf75 |
| Maven | org.pac4j:pac4j-core | 6.4.1 | GHSA-xw5c-jc7x-gf75 |
Affected products (as reported)
Weakness: CWE-352 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N
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.html vendor-advisory