CVE-2026-40458 HIGH

CVE-2026-40458: Cross-Site Request Forgery in PAC4J

Vendor Pac4J
Product PAC4J
Weakness CWE-352 · CSRF
Published April 17, 2026
Last update April 17, 2026

CVSS base score

7.0/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction
Confidentiality
Integrity

CVSS 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

What the vulnerability does

01Description

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

Key dates

02Disclosure timeline

April 17, 2026 CVE published
April 17, 2026 Record updated

Related vulnerabilities

04Related CVE