CVE-2026-40458

6.5 MEDIUM
Published: April 17, 2026 Modified: April 20, 2026
View on NVD

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

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory

2 reference(s) from NVD

Quick Stats

CVSS v3 Score
6.5 / 10.0
EPSS (Exploit Probability)
0.2%
6th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

pac4j