GHSA-FMG6-246M-9G2V: GHSA-FMG6-246M-9G2V: Insufficient Entropy in Cookie Encryption in Auth0 Laravel SDK

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GHSA-FMG6-246M-9G2V: Insufficient Entropy in Cookie Encryption in Auth0 Laravel SDK

Vulnerability ID: GHSA-FMG6-246M-9G2V
CVSS Score: 7.7
Published: 2026-04-03

The Auth0 Laravel SDK (auth0/login) suffers from a cryptographic vulnerability due to insufficient entropy in its cookie encryption mechanism. This weakness permits threat actors to brute-force session encryption keys offline, enabling the forgery of session cookies and leading to complete account takeover.

TL;DR

A high-severity flaw in the Auth0 Laravel SDK (< 7.21.0) uses weak entropy for session cookie encryption. Attackers with access to a valid encrypted cookie can brute-force the key offline to forge sessions and impersonate users.

Technical Details

CWE ID: CWE-331
Attack Vector: Network
CVSS Score: 7.7 (High)
Attack Complexity: High
Exploit Status: None/Private
KEV Status: Not Listed

Affected Systems

Auth0 Laravel SDK (auth0/login)
Laravel Framework integrating Auth0
auth0/login: >= 7.0.0, <= 7.20.0 (Fixed in: 7.21.0)

Mitigation Strategies

Upgrade the auth0/login SDK to a patched version
Rotate application and session encryption keys
Purge and invalidate all existing active sessions
Monitor access logs for unexpected privilege usage or session anomalies

Remediation Steps:

Run 'composer update auth0/login' to bring the package to version 7.21.0 or higher.
Generate new, high-entropy cryptographic keys for application session handling (e.g., APP_KEY in Laravel).
Deploy the updated application and environment variables.
Clear server-side session stores or caches to force re-authentication for all users.
Review authentication logs for anomalous access patterns originating from static sessions.