Auth0-PHP is a PHP SDK for Auth0 Authentication and Management APIs. Versions 8.0.0-BETA3 prior to 8.3.1 contain a vulnerability due to insecure deserialization of cookie data. If exploited, since SDKs process cookie content without prior authentication, a threat actor could send a specially crafted cookie containing malicious serialized data. Applications using the Auth0-PHP SDK are affected, as are applications using the Auth0/symfony, Auth0/laravel-auth0, or Auth0/wordpress SDKs, because those SDKsrely on the Auth0-PHP SDK versions from 8.0.0-BETA3 until 8.14.0. Version 8.3.1 contains a patch for the issue.