CVE-2020-15240

Name: CVE-2020-15240
Creator: NVD / NIST
Published: 2020-10-21T18:15:12.813+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.1/10EPSS 0.79%

Last modified Jun 17, 2026

CVE-2020-15240 is a critical-severity vulnerability rated 9.1/10 on the CVSS scale. 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. EPSS estimates a 0.79% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS Probability

0.79%

51.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Auth0	Omniauth-Auth0	>= 2.3.0, < 2.4.1

References

https://github.com/auth0/omniauth-auth0/commit/fd3a14f4ccdfbc515d1121d6378ff88bf55a7a7aPatch, Third Party Advisory
https://github.com/auth0/omniauth-auth0/security/advisories/GHSA-58r4-h6v8-jcvmThird Party Advisory
https://rubygems.org/gems/omniauth-auth0Product, Vendor Advisory
https://github.com/auth0/omniauth-auth0/commit/fd3a14f4ccdfbc515d1121d6378ff88bf55a7a7aPatch, Third Party Advisory
https://github.com/auth0/omniauth-auth0/security/advisories/GHSA-58r4-h6v8-jcvmThird Party Advisory
https://rubygems.org/gems/omniauth-auth0Product, Vendor Advisory

Timeline

Published: Oct 21, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-15240?

How severe is CVE-2020-15240?

CVE-2020-15240 has a CVSS score of 9.1/10 (CRITICAL severity). The EPSS model estimates a 0.79% probability of exploitation in the next 30 days.

How do I fix CVE-2020-15240?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-15240?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST