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CVE-2026-19804: s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions

Severity

8.8 (HIGH)

Vendor

CLAVAQUE

Affected versions

0 through 260814

Patch status

Unknown

Published

2026-09-25T08:16:40.383

Modified

2026-09-25T08:16:40.383

Why it matters

This matters because the affected product may be exposed on public websites. A vulnerable plugin can create a direct path to site compromise, malicious code deployment, or data theft.

Recommended admin actions

• Review and patch based on exposure, asset criticality, and business impact.
• Check whether the affected WordPress plugin or theme is installed.
• Update, disable, or remove the affected component if present.
• Compare installed versions against the affected version range in the advisory.
• Treat internet-facing systems as higher priority.

Technical summary

The s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 260814 via the 'first_name' parameter parameter. This is due to insufficient sanitization of the first_name parameter via esc_refs(), which strips only regex backreferences and not PHP tags, before substitution into the eval'd Signup Tracking Codes template, combined with disclosure of the site-global proxy verification key that allows PayPal postback verification to be bypassed. This makes it possible for unauthenticated attackers to execute code on the server. Successful exploitation requires that the site administrator has configured a Signup Tracking Codes template containing the %%first_name%% placeholder (a documented, GUI-supported feature) and that the attacker has obtained the site-global proxy verification key, which is exposed in plaintext in the JSON response of any PayPal Checkout AJAX request on the target site.

View the official NVD record for CVE-2026-19804

CVE data is sourced from NVD/CNA records and optional enrichment. Validate against the vendor advisory before taking production action.