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Regression in JWT Signature Validation

High severity GitHub Reviewed Published Oct 21, 2020 in auth0/omniauth-auth0 • Updated May 4, 2023

Package

bundler omniauth-auth0 (RubyGems)

Affected versions

>= 2.3.0, < 2.4.1

Patched versions

2.4.1

Description

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.

References

@lzychowski lzychowski published to auth0/omniauth-auth0 Oct 21, 2020
Published by the National Vulnerability Database Oct 21, 2020
Reviewed Oct 27, 2020
Published to the GitHub Advisory Database Nov 3, 2020
Last updated May 4, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(25th percentile)

Weaknesses

Improper Authentication

When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Learn more on MITRE.

Improper Verification of Cryptographic Signature

The product does not verify, or incorrectly verifies, the cryptographic signature for data. Learn more on MITRE.

CVE ID

CVE-2020-15240

GHSA ID

GHSA-58r4-h6v8-jcvm

Source code

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