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

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History

Fri, 17 Apr 2026 15:00:00 +0000

Type Values Removed Values Added
First Time appeared Pac4j
Pac4j pac4j
Vendors & Products Pac4j
Pac4j pac4j

Fri, 17 Apr 2026 14:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 17 Apr 2026 13:45:00 +0000

Type Values Removed Values Added
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
Title Cross-Site Request Forgery in PAC4J
Weaknesses CWE-352
References
Metrics cvssV4_0

{'score': 7, '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'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: CERT-PL

Published:

Updated: 2026-04-17T14:00:04.811Z

Reserved: 2026-04-13T10:06:07.141Z

Link: CVE-2026-40458

cve-icon Vulnrichment

Updated: 2026-04-17T13:59:26.592Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-04-17T14:16:33.987

Modified: 2026-04-17T15:38:09.243

Link: CVE-2026-40458

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-04-17T14:45:20Z

Weaknesses