CVE-2026-18467: Paytium: Mollie payment forms & donations <= 5.0.3 - Unauthenticated Privilege Escalation via 'pt_form_field[pt-user-role]' Parameter

Vulnerability summary

CVE-2026-18467 is a critical (CVSS 9.8) Improper Privilege Management vulnerability in paytiumsupport paytium: mollie payment forms & donations. EPSS estimates a 0.39% chance of exploitation in the next 30 days, higher than 32.2% of scored vulnerabilities. Fixed in 5.0.4.

Timeline

1. 24-09-2026
   PublishedVulnerability first disclosed.
2. 24-09-2026
   Last modifiedVulnerability information updated.

Description

The Paytium: Mollie payment forms & donations plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 5.0.3. The 5.0.3 patch introduced a wp_hash()/hash_equals() signature gate on the pt-paytium-user-data field, but left a second filter — pt_cf_checkout_meta(), registered on the pt_meta_values hook after the signed builder — that copies every $_POST['pt_form_field'][*] key verbatim into the payment meta array without any signature verification; this allows the pt-user-role value it copies to overwrite the signed path's output, after which paytium_user_data_processing() reads the persisted _pt-user-role post meta and passes it directly as the role argument to wp_insert_user(). This makes it possible for unauthenticated attackers to register a new WordPress account with the administrator role and fully take over the site. Exploitation requires submitting a payment through a publicly-exposed [paytium] shortcode form and completing the resulting payment flow, after which the attacker can seize the new administrator account via the standard lost-password flow on their supplied email address.

• CWE-269Improper Privilege ManagementThe product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.