EUVD-2026-23421
CVSS VectorNVD
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
2DescriptionNVD
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
AnalysisAI
CSRF token bypass in PAC4J authentication library (versions 5.0-5.7.9 and 6.0-6.4.0) allows remote attackers to perform unauthorized state-changing operations via hash collision exploitation. Attackers craft tokens that collide with victims' legitimate CSRF tokens by exploiting Java's deterministic String.hashCode() function, reducing effective security from cryptographic strength to 32 bits. …
Sign in for full analysis, threat intelligence, and remediation guidance.
RemediationAI
Within 24 hours: Inventory all applications using PAC4J and identify those running versions 5.0-5.7.9 or 6.0-6.4.0. Within 7 days: Upgrade PAC4J to version 5.7.10 or 6.4.1 (or later) and test in staging environment. …
Sign in for detailed remediation steps.
Share
External POC / Exploit Code
Leaving vuln.today