PT-2026-33451 · Pac4J · Pac4J

Published 2026-04-17 · Updated 2026-04-17 · CVE-2026-40458

Mitre

CVSS v4.0

7.0

High

AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N

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

Fix

CSRF

Weakness Enumeration

CWE-352

Related Identifiers

CVE-2026-40458

Affected Products

Pac4J

References · 4

• https://nvd.nist.gov/vuln/detail/CVE-2026-40458 · Security Note
• https://pac4j.org/blog/security-advisory-pac4j-core-and-ldap.html · Vendor Advisory
• https://cert.pl/en/posts/2026/04/CVE-2026-40458 · Note
• https://twitter.com/VulmonFeeds/status/2045214505475424575 · Twitter Post