CVE-2026-19804
Description
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
References
- https://plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-checkout-in.inc.php#L736
- https://plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-return-in-subscr-or-wa-w-level.inc.php#L311
- https://plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-return-in-subscr-or-wa-w-level.inc.php#L319
- https://plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-return-in.inc.php#L47
- https://plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-utilities.inc.php#L185
- https://plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-utilities.inc.php#L92
- https://plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/tracking-codes.inc.php#L71
- https://plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/utilities.inc.php#L49
- https://plugins.trac.wordpress.org/changeset?reponame=&old=3671073%40s2member&new=3671073%40s2member
- https://www.wordfence.com/threat-intel/vulnerabilities/id/e87da8fa-04cc-4b9a-9dde-be7d4f2bd76e?source=cve
CWEs
CWE-94
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.