s2Member <= 260814 - Unauthenticated Remote Code Execution via 'first_name' Parameter in PayPal Proxy Return
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-94.
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| clavaque | s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions | up to 260814 | — | No fix listed | CNA |
- s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions Vendorclavaque Affected up to 260814 Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2026-19804
- 2026-10-03 Alias added: GHSA-fgx2-6hhq-hwhw
References
Other 10
- https://www.wordfence.com/threat-intel/vulnerabilities/id/e87da8fa-04cc-4b9a-9dde-be7d4f2bd76e?source=cve
- https://plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/utilities.inc.php#L49
- 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/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-utilities.inc.php#L92
- 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-checkout-in.inc.php#L736
- https://plugins.trac.wordpress.org/browser/s2member/trunk/src/includes/classes/paypal-return-in.inc.php#L47
- https://plugins.trac.wordpress.org/changeset?reponame=&old=3671073%40s2member&new=3671073%40s2member
More clavaque vulnerabilities
- TI-2026-01651 s2Member <= 260127 - Unauthenticated Privilege Escalation via Account Takeover CVSS 3.1CRITICAL 9.8
- TI-2026-84120 Code injection in s2Member plugin via item_name IPN parameter CVSS 3.1CRITICAL 9.8
- TI-2024-07720 Information disclosure in clavaque s2Member – Excellent for All Kinds of Memberships… CVSS 3.1HIGH 8.8
- TI-2024-00828 Improper access control in clavaque s2Member – Excellent for All Kinds of Memberships… CVSS 3.1MEDIUM 5.3
- TI-2026-81740 Stored cross-site scripting in s2Member WordPress plugin CVSS 3.1MEDIUM 6.4
- TI-2025-12552 s2Member <= 251005 - Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode CVSS 3.1MEDIUM 6.4
Sources
- CVE-2026-19804 · CVE Program
- CVE-2026-19804 · NVD
- FIRST EPSS
- GHSA-fgx2-6hhq-hwhw · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences