CVE-2026-1321: stellarwp membership plugin – restrict content Missing Authorization

Vulnerability summary

CVE-2026-1321 is a high (CVSS 8.1) Missing Authorization vulnerability in stellarwp membership plugin – restrict content. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 28.7% of scored vulnerabilities.

Timeline

1. 05-03-2026
   PublishedVulnerability first disclosed.
2. 08-04-2026
   Last modifiedVulnerability information updated.

Description

The Membership Plugin – Restrict Content plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 3.2.20. This is due to the `rcp_setup_registration_init()` function accepting any membership level ID via the `rcp_level` POST parameter without validating that the level is active or that payment is required. Combined with the `add_user_role()` method which assigns the WordPress role configured on the membership level without status checks, this makes it possible for unauthenticated attackers to register with any membership level, including inactive levels that grant privileged WordPress roles such as Administrator, or paid levels that charge a sign-up fee. The vulnerability was partially patched in version 3.2.18.

• CWE-862Missing AuthorizationThe product does not perform an authorization check when an actor attempts to access a resource or perform an action.