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CVE-2026-19804— s2Member <= 260814 - Unauthenticated Remote Code Execution via 'first_name' Parameter in PayPal Proxy Return

Quick assessment

Affected
clavaque s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

WordPress 插件 s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions 在所有版本直至并包括 260814 版本中，存在通过 参数导致远程代码执行（RCE）的安全漏洞。该漏洞的产生原因是： 参数在通过 函数进行清理时，仅移除了正则表达式中的反向引用（regex backreferences），而未过滤 PHP 标签；随后该参数被代入由 执行的“

CVSS 8.8 · High EPSS 1.04% · P63

Affected Version Matrix 1

VendorProduct Version RangeStatus
clavaque s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions ≤ 260814 affected
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I. Basic Information for CVE-2026-19804

Vulnerability Information
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Vulnerability Title
s2Member <= 260814 - Unauthenticated Remote Code Execution via 'first_name' Parameter in PayPal Proxy Return
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
对生成代码的控制不恰当(代码注入)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
clavaque s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions 0 ~ 260814 -

II. Public POCs for CVE-2026-19804

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III. Intelligence Information for CVE-2026-19804

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Patches & Fixes for CVE-2026-19804 (5)

Vendor Advisories for CVE-2026-19804 (1)

IV. Related Vulnerabilities

Same product: s2Member – Excellent for All Kinds of Memberships, Content Restriction Paywalls & Member Access Subscriptions
Same vendor: clavaque
Same weakness: CWE-94

V. Comments for CVE-2026-19804

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