CVE-2020-15240: Regression in JWT Signature Validation
Overview Versions after and including 2.3.0 are improperly validating the JWT token signature when using the JWTValidator.verify method. Improper validation of the JWT token signature when not using the default Authorization Code Flow can allow an attacker to bypass authentication and authorization.
Am I affected? You are affected by this vulnerability if all of the following conditions apply:
- You are using omniauth-auth0. - You are using JWTValidator.verify method directly OR you are not authenticating using the SDK’s default Authorization Code Flow.
How to fix that? Upgrade to version 2.4.1.
Will this update impact my users? The fix provided in this version will not affect your users.
Other sources
omniauth-auth0 (rubygems) versions >= 2.3.0 and < 2.4.1 improperly validate the JWT token signature when using the jwtvalidator.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 Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2020-15240?
CVE-2020-15240 has a medium severity due to improper validation of JWT token signatures.
How do I fix CVE-2020-15240?
To fix CVE-2020-15240, update the Auth0 Omniauth-auth0 gem to version 2.4.1 or later.
What software is affected by CVE-2020-15240?
CVE-2020-15240 affects versions 2.3.0 to 2.4.0 of the Auth0 Omniauth-auth0 gem.
What could an attacker do with CVE-2020-15240?
An attacker could potentially bypass authentication by exploiting the improper validation of the JWT token signature.
Is CVE-2020-15240 related to JWT token handling?
Yes, CVE-2020-15240 specifically involves improper validation of JWT token signatures.