Executive brief
Wishlist Member is a WordPress plugin used to manage membership sites with content protection and payment integration. A critical vulnerability in the registration function allows unauthenticated attackers to take over any WordPress account, including administrator accounts, by exploiting improper validation of user parameters. Attackers can hijack accounts without needing to know passwords, compromising all site data and enabling complete control of affected WordPress installations.
Technical details
The vulnerability exists in the wpm_register() function, which validates the registration cookie against the GET reg parameter but fails to verify that the mergewith and wpm_id POST parameters reference a temporary or incomplete registrant tied to the current transaction. An unauthenticated attacker can supply an arbitrary user ID as the mergewith value, causing wp_update_user() to overwrite the target account's username, password, email, first name, and last name with attacker-controlled values. Password and email change notifications are explicitly suppressed. When wpm_id references a non-existent membership level, no role key is added to the update payload, preserving the target user's existing role—including administrator—resulting in direct privilege escalation. The vulnerability affects Wishlist Member versions up to and including 3.34.1.
Affected products
- Wishlist Wishlist Member up to and including 3.34.1
Timeline
- 2026-08-14: disclosed