s2Member <= 260814 - Unauthenticated Remote Code Execution via 'first_name' Parameter in PayPal Proxy Return

Summary

CVE	CVE-2026-19804
State	PUBLISHED
Assigner	Wordfence
Source Priority	CVE Program / NVD first with legacy fallback
Published	2026-09-25 08:16:40 UTC
Updated	2026-09-25 14:17:18 UTC
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.

Primary CVSS: v3.1 8.8 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.010400000 probability, percentile 0.625640000 (date 2026-09-27)

Problem Types: CWE-94 | CWE-94 CWE-94 Improper Control of Generation of Code ('Code Injection')

Version	Source	Type	Score	Severity	Vector
3.1	[email protected]	Secondary	8.8	HIGH	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`
3.1	CNA	DECLARED	8.8	HIGH	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Source	Vendor	Product	Version	Platforms
CNA	Clavaque	S2Member Excellent For All Kinds Of Memberships Content Restriction Paywalls Member Access Subscriptions	affected 260814 semver	Not specified

Reference	Source	Link	Tags
www.wordfence.com/threat-intel/vulnerabilities/id/e87da8fa-04cc-4b9a-9dde-be7d4...	[email protected]	www.wordfence.com
plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/utilities.inc.php	[email protected]	plugins.trac.wordpress.org
plugins.trac.wordpress.org/changeset	[email protected]	plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/tracking-codes.in...	[email protected]	plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-checkout-i...	[email protected]	plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-return-in-...	[email protected]	plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-utilities....	[email protected]	plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-return-in....	[email protected]	plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-return-in-...	[email protected]	plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-utilities....	[email protected]	plugins.trac.wordpress.org
CVE Program record	CVE.ORG	www.cve.org	canonical
NVD vulnerability detail	NVD	nvd.nist.gov	canonical, analysis

CNA: Supakiad S. (m3ez) (en)

Source	Time	Event
CNA	2026-09-24T18:56:33.000Z	Disclosed

There are currently no legacy QID mappings associated with this CVE.