CVE-2020-15240: AUTH0 Omniauth-AUTH0

Critical severity, CVSS 9.1. EPSS: 0.8% chance of exploitation in the next 30 days.

omniauth-auth0 (rubygems) versions >= 2.3.0 and < 2.4.1 improperly validate the JWT token signature when using the `jwt_validator.verify` method. Improper validation of the JWT token signature can allow an attacker to bypass authentication and authorization. You are affected by this vulnerability if all of the following conditions apply: 1. You are using `omniauth-auth0`. 2. You are using `JWTValidator.verify` method directly OR you are not authenticating using the SDK’s default Authorization Code Flow. The issue is patched in version 2.4.1.

Affected products

• AUTH0 Omniauth-AUTH0: from 2.3.0, before 2.4.1 (fixed in 2.4.1)

Published 2020-10-21. Last modified 2026-06-17.