CVE-2026-19804 json
s2Member <= 260814 - Unauthenticated Remote Code Execution via 'first_name' Parameter in PayPal Proxy Return
published 2026-09-25 45 d ago modified 2026-09-25 44 d ago also EUVD-2026-86577
- cvss
- 8.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.0%
- EPSS 1.0% chance of exploitation in 30 days, percentile 64%
- public exploits
- 0
- none known
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.
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 44 d ago
Exploit prediction
1.04% chance of exploitation in the next 30 days, higher than 64% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected products
- clavaque s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions
Classification
- Weakness
-
- CWE-94 Improper Control of Generation of Code
- Technology feeds
References
- wordfence.com /threat-intel/vulnerabilities/id/e87da8fa-04cc-4b9a-9dde-be7d4f2bd76e?source=cve
- plugins.trac.wordpress.org /browser/s2member/trunk/src/includes/classes/utilities.inc.php#L49
- plugins.trac.wordpress.org /browser/s2member/trunk/src/includes/classes/tracking-codes.inc.php#L71
- plugins.trac.wordpress.org /browser/s2member/trunk/src/includes/classes/paypal-return-in-subscr-or-wa-w-level.inc.php#L311
- plugins.trac.wordpress.org /browser/s2member/trunk/src/includes/classes/paypal-return-in-subscr-or-wa-w-level.inc.php#L319
- plugins.trac.wordpress.org /browser/s2member/trunk/src/includes/classes/paypal-utilities.inc.php#L92
- plugins.trac.wordpress.org /browser/s2member/trunk/src/includes/classes/paypal-utilities.inc.php#L185
- plugins.trac.wordpress.org /browser/s2member/trunk/src/includes/classes/paypal-checkout-in.inc.php#L736
- plugins.trac.wordpress.org /browser/s2member/trunk/src/includes/classes/paypal-return-in.inc.php#L47
- plugins.trac.wordpress.org /changeset?reponame=&old=3671073%40s2member&new=3671073%40s2member
Sources
- CVE List CVE-2026-19804
- NVD CVE-2026-19804
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.