CVE-2024-54303: Simple Payment Plugin XSS Vulnerability

CVE-2024-54303 Overview

CVE-2024-54303 is a reflected Cross-Site Scripting (XSS) vulnerability in the Ido Kobelkowsky Simple Payment WordPress plugin. The flaw stems from improper neutralization of user-supplied input during web page generation [CWE-79]. It affects all plugin versions up to and including 2.3.8.

An attacker can craft a malicious URL that, when visited by an authenticated or unauthenticated victim, executes attacker-controlled JavaScript in the victim's browser. The vulnerability requires user interaction and changes the security scope, allowing impact beyond the vulnerable component.

Critical Impact

Successful exploitation allows attackers to execute arbitrary JavaScript in the victim's browser session, enabling session theft, credential harvesting, and unauthorized actions performed under the victim's privileges.

Affected Products

• Ido Kobelkowsky Simple Payment plugin for WordPress
• All versions from initial release through 2.3.8
• WordPress sites with the simple-payment plugin installed and active

Discovery Timeline

• 2024-12-13 - CVE-2024-54303 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2024-54303

Vulnerability Analysis

The vulnerability is a reflected XSS issue in the Simple Payment plugin's request handling. User-controlled input is rendered into the HTML response without proper output encoding or sanitization. The plugin reflects attacker-controlled values from HTTP request parameters directly into the generated page.

Because the attack triggers in the victim's browser, the impact spans confidentiality, integrity, and availability of session data and any resources the victim can access. The changed scope indicates that exploitation can affect resources outside the immediate vulnerable component, such as the WordPress admin context or other site cookies.

Root Cause

The root cause is missing or insufficient input validation and output encoding in the plugin's request-handling code paths. Input received via HTTP parameters is concatenated into HTML output without applying WordPress sanitization helpers such as esc_html(), esc_attr(), or wp_kses(). This allows HTML and JavaScript characters to break out of their intended context.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker crafts a URL containing a malicious payload in a vulnerable parameter and delivers it through phishing emails, social media, or third-party sites. When the victim clicks the link, the plugin reflects the payload into the response, and the browser executes it.

The vulnerability mechanism involves unsanitized parameter values being echoed into the HTTP response. Refer to the Patchstack XSS Vulnerability Report for additional technical details.

Detection Methods for CVE-2024-54303

Indicators of Compromise

• HTTP request logs containing <script>, javascript:, onerror=, or encoded variants in query parameters targeting simple-payment plugin endpoints.
• Unexpected outbound requests from user browsers to attacker-controlled domains after interacting with WordPress pages.
• Referrer headers pointing to external phishing or redirector domains preceding suspicious session activity.

Detection Strategies

• Inspect web server access logs for URL parameters containing HTML tags, event handlers, or URL-encoded JavaScript directed at simple-payment routes.
• Deploy a Web Application Firewall (WAF) rule set to flag and block reflected XSS payloads targeting WordPress plugin parameters.
• Use Content Security Policy (CSP) violation reports to identify in-browser script execution attempts on pages served by the plugin.

Monitoring Recommendations

• Monitor administrator session activity for anomalous actions performed shortly after clicking external links.
• Track plugin version inventories across WordPress installations to identify hosts still running simple-payment versions up to 2.3.8.
• Alert on WordPress audit log events showing privilege changes, new user creation, or theme/plugin modifications without corresponding admin console activity.

How to Mitigate CVE-2024-54303

Immediate Actions Required

• Identify all WordPress sites running the Simple Payment plugin and verify the installed version.
• Disable or remove the plugin on any site running version 2.3.8 or earlier until a fixed release is confirmed.
• Force a password reset and session invalidation for WordPress administrators if suspicious requests are found in logs.

Patch Information

At the time of publication, the advisory indicates the vulnerability affects all versions through 2.3.8 with no patched release explicitly listed. Check the Patchstack advisory and the plugin's official WordPress repository page for the latest fixed version before re-enabling.

Workarounds

• Deploy WAF rules that block requests containing common XSS payload patterns to plugin URLs.
• Implement a strict Content Security Policy that disallows inline scripts and restricts script sources to trusted origins.
• Restrict access to the WordPress site or vulnerable endpoints via IP allowlisting until the plugin is updated or removed.

# Example WAF / ModSecurity rule to block reflected XSS payloads on simple-payment endpoints
SecRule REQUEST_URI "@contains /simple-payment" \
  "chain,id:1005430,phase:2,deny,status:403,log,msg:'CVE-2024-54303 Simple Payment XSS attempt'"
SecRule ARGS "@rx (?i)(<script|onerror=|javascript:|%3Cscript)" "t:none,t:urlDecodeUni"