{"id":"CVE-2020-15240","aliases":["GHSA-58r4-h6v8-jcvm"],"url":"https://o3.security/vulnerability/CVE-2020-15240","summary":"Regression in JWT Signature Validation","details":"### Overview\nVersions 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.\n\n### Am I affected?\nYou are affected by this vulnerability if all of the following conditions apply:\n\n- You are using `omniauth-auth0`.\n- You are using `JWTValidator.verify` method directly OR you are not authenticating using the SDK’s default Authorization Code Flow.\n\n### How to fix that?\nUpgrade to version `2.4.1`.\n\n### Will this update impact my users?\nThe fix provided in this version will not affect your users.","published":"2020-10-21T18:15:12.813Z","modified":"2026-07-09T06:34:42.489654Z","cvss":{"score":9.1,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"RubyGems","name":"omniauth-auth0","fixedVersion":"2.4.1"}],"fix":{"url":"https://github.com/auth0/omniauth-auth0/commit/fd3a14f4ccdfbc515d1121d6378ff88bf55a7a7a","label":"auth0/omniauth-auth0@fd3a14f"},"references":[{"type":"ADVISORY","url":"https://github.com/auth0/omniauth-auth0/security/advisories/GHSA-58r4-h6v8-jcvm"},{"type":"ADVISORY","url":"https://rubygems.org/gems/omniauth-auth0"},{"type":"FIX","url":"https://github.com/auth0/omniauth-auth0/commit/fd3a14f4ccdfbc515d1121d6378ff88bf55a7a7a"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2020-15240"},{"type":"PACKAGE","url":"https://github.com/auth0/omniauth-auth0"},{"type":"WEB","url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/omniauth-auth0/CVE-2020-15240.yml"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-09T06:34:42.489654Z"}}