User Registration & Membership <= 5.2.8 — Authenticated (Subscriber+) Arbitrary Shortcode Execution via Referer Header via 'referrer_url' Smart Tag

Am I affected?

• Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under User Registration & Membership – Free & Paid Memberships, Subscriptions, Content Restriction, User Profile, Custom User Registration & Login Builder.
• No admin access? Run a passive check of your site. It reads public files only.

What to do

1. Update to version 5.3.0, or a newer patched version
2. Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
3. Watch User Registration & Membership – Free & Paid Memberships, Subscriptions, Content Restriction, User Profile, Custom User Registration & Login Builder to get an email when the next vulnerability is published.

Advisory

Source description from Wordfence Intelligence, credited to Passakorn Yookindee.

The User Registration & Membership plugin for WordPress is vulnerable to Arbitrary Shortcode Execution in versions up to, and including, 5.2.8 This is due to insufficient input sanitization in the 'referrer_url' branch of UR_Smart_Tags::process(), where the attacker-controlled HTTP_REFERER header is only passed through sanitize_text_field() — which does not strip WordPress shortcode delimiters — before being substituted into a Content Restriction message that is subsequently executed via apply_shortcodes()/do_shortcode(). This makes it possible for unauthenticated attackers to execute arbitrary registered shortcodes on any restricted page whose message uses the supported {{referrer_url}} smart tag.

Exploits & references

Proof-of-concept & detection

No public proof-of-concept or detection template is known for this vulnerability.

Advisories & patches

• Advisorywordfence.com

Related CVEs

Timeline

1. Oct 16, 2026

   CVE published

   Severity high, CVSS 8.1

2. Nov 13, 2026

   Record last updated