CVE-2026-120070: User Frontend <= 4.3.13 - Authenticated (Subscriber+) Privilege Escalation via post_content Parameter

The User Frontend – Membership, User Registration, User Profile, User Directory & Content Restriction with Frontend Post Submission plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 4.3.13 via the postcontent parameter of the submitpost() function. The vulnerability exists because the protected-shortcode blocklist guard inspects the sanitizetextareafield() copy of the submitted postcontent, while the copy actually persisted to the database is processed through wpkses(), whose wpksesnonull() step strips C0 control bytes — allowing an attacker to inject a single \x01 byte inside the [wpuf-registration] tag name to defeat the strpos() blocklist check while the clean, functional shortcode is stored verbatim; stripshortcodes() does not neutralize the stored shortcode either, because the Frontend container that registers it via addshortcode() is only instantiated when isadmin() is false, and admin-ajax requests have isadmin() === true. This makes it possible for authenticated attackers, with Subscriber-level access and above, to inject a [wpuf-registration role="editor"] shortcode into a published post, causing a live Editor-role registration form to be rendered publicly on the frontend that any visitor — or the attacker themselves — can submit to mint a WordPress Editor account with an immediately active privileged session when the default autologinafterregistration setting is enabled.