CVE-2020-15240 Regression in JWT Signature Validation
Attackers can bypass authentication and authorization by exploiting improper JWT signature validation in specific usage scenarios.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2020-15240?
CVE-2020-15240 is a high-severity authentication bypass vulnerability in omniauth-auth0, published on 21 Oct 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2020-15240?
2 open source packages ship an affected version, including omniauth-auth0. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
omniauth-auth0 RubyGems | From 2.3.0 | 2.4.1 |
omniauth-auth0 RubyGems | From 2.3.0 | 2.4.1 |
Products include Auth0 Omniauth-Auth0.
How do I fix CVE-2020-15240?
Upgrade omniauth-auth0 to 2.4.1 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2020-15240 being exploited?
There is no known exploitation of CVE-2020-15240 in the wild and no public exploit code.
Sources
Also known as GHSA-58r4-h6v8-jcvm.