The Jupiter X Core plugin for WordPress is vulnerable to Authentication Bypass via the Twitter/X Social Login handler in all versions up to and including 4.61.0. The vulnerability exists within the verify_twitter_callback function because after exchanging the visitor's oauth_verifier for their access token, the handler never calls setOauthToken() to reassign the returned credentials to the TwitterOAuth client, causing the subsequent account/verify_credentials API call to remain signed with the site operator's stored Access Token and Access Token Secret rather than the authenticating visitor's token. This causes the X API to return the profile of the X application owner instead of the signing-in visitor, and the plugin then resolves and authenticates a WordPress account solely by matching that owner's email address via wp_set_auth_cookie(), allowing unauthenticated attackers to gain authenticated access as the WordPress user whose email corresponds to the X app owner, who is typically the site administrator.