Forminator Forms <= 1.58.1 - Unauthenticated Arbitrary Shortcode Execution via 'User-Agent' Header and 'referer_url' Parameter via Quiz Notification Merge Tags

Summary

The Forminator Forms – Contact Form, Payment Form & Custom Form Builder plugin for WordPress is vulnerable to Arbitrary Shortcode Execution in versions up to, and including, 1.58.1. This is due to the forminator_replace_quiz_form_data() helper invoking do_shortcode() on the fully expanded notification body once the {quiz_result} merge tag has been substituted, while the earlier-substituted {user_agent} and {refer_url} merge tags carry unauthenticated attacker-controlled bytes (the User-Agent header and the referer_url POST parameter) through sanitize_text_field()/esc_html(), neither of which strip the '[' and ']' shortcode delimiters. This makes it possible for unauthenticated attackers to execute arbitrary WordPress shortcodes registered on the site by submitting a quiz whose notification template contains {quiz_result}; the resulting impact depends on the shortcodes exposed by other installed plugins/themes and can range from arbitrary content injection to information disclosure.

Timeline

1. Oct 16, 2026, 4:26 AM UTCCVE published
2. Oct 16, 2026, 2:51 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Oct 16, 2026, 3:09 PM UTCRecord last updated

Affected versions

• wpmudev Forminator Forms – Contact Form, Payment Form & Custom Form Builder

  through 1.58.1

References 7