CVE-2025-50019: Simple Sticky Footer Stored XSS Vulnerability

CVE-2025-50019 Overview

CVE-2025-50019 is a stored Cross-Site Scripting (XSS) vulnerability affecting the Sandor Kovacs Simple Sticky Footer plugin for WordPress. The flaw stems from improper neutralization of user-supplied input during web page generation, classified under [CWE-79]. All versions up to and including 1.3.5 are affected. An authenticated attacker with high privileges can inject malicious script content that persists in the plugin's stored data. When rendered, the payload executes in the browser context of site visitors and administrators, enabling session-based attacks against other users.

Critical Impact
A high-privileged authenticated user can inject persistent JavaScript that executes across administrative and visitor sessions, enabling session theft, defacement, and further account compromise.

Affected Products

Sandor Kovacs Simple Sticky Footer WordPress plugin
All versions from initial release through 1.3.5
WordPress sites using the simple-sticky-footer plugin

Discovery Timeline

2025-06-20 - CVE-2025-50019 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-50019

Vulnerability Analysis

The Simple Sticky Footer plugin accepts user-controlled input intended for display in the site footer. The plugin fails to properly sanitize or encode this input before rendering it into HTML output. As a result, attackers can inject script tags or event handler attributes that browsers interpret and execute as JavaScript. Because the injected payload is stored server-side, execution occurs on every page load without further attacker interaction.

The attack requires high privileges, meaning the attacker must already hold an authenticated account with configuration rights to the plugin. User interaction is also required for exploitation of the injected payload. The scope change indicates that a successful attack impacts resources beyond the vulnerable component itself, such as visitor sessions or administrative interfaces sharing the same origin.

Root Cause

The root cause is missing output encoding when plugin-configured content is written into the DOM. WordPress provides functions such as esc_html(), esc_attr(), and wp_kses() for context-appropriate escaping, but the plugin appears to render stored footer content without applying these filters. Any HTML markup submitted through the plugin's settings interface is preserved verbatim and served to browsers.

Attack Vector

Exploitation requires an attacker with administrator or equivalent privileges to access the plugin's configuration interface. The attacker submits a payload containing JavaScript, for example a <script> element or an event handler on an HTML tag. The payload persists in WordPress options storage. When any user loads a page that renders the sticky footer, the browser parses and executes the injected script under the site's origin. Refer to the Patchstack XSS Vulnerability Report for additional technical context.

Detection Methods for CVE-2025-50019

Indicators of Compromise

Unexpected <script> tags, on* event handlers, or javascript: URIs stored in the simple_sticky_footer plugin options within the WordPress wp_options table
Outbound browser requests to attacker-controlled domains originating from pages that render the site footer
Modifications to plugin settings by administrator accounts outside normal change windows

Detection Strategies

Review the WordPress database wp_options table for entries associated with the Simple Sticky Footer plugin and inspect stored values for HTML or JavaScript content
Deploy a Web Application Firewall (WAF) rule to log and block requests containing script payloads submitted to wp-admin/options.php or plugin-specific settings endpoints
Monitor rendered pages for unexpected inline scripts using Content Security Policy (CSP) violation reports

Monitoring Recommendations

Enable WordPress audit logging to capture administrator changes to plugin configuration
Alert on any modification to Simple Sticky Footer settings by non-administrative accounts or unfamiliar administrators
Track login sessions for privileged accounts and correlate with plugin configuration changes

How to Mitigate CVE-2025-50019

Immediate Actions Required

Identify all WordPress sites running the Simple Sticky Footer plugin at version 1.3.5 or earlier
Deactivate and remove the plugin until a patched version is confirmed available from the vendor
Audit administrator accounts and rotate credentials for any account that may have been used to inject a payload
Inspect plugin option values in the database and clear any content containing script tags or event handlers

Patch Information

At the time of publication, the Patchstack advisory lists all versions from initial release through 1.3.5 as vulnerable. Monitor the Patchstack advisory and the plugin listing on WordPress.org for a fixed release. Apply the patch immediately once available.

Workarounds

Uninstall the Simple Sticky Footer plugin and replace it with a maintained alternative that applies proper output escaping
Restrict administrator accounts to trusted personnel and enforce multi-factor authentication on all privileged WordPress logins
Deploy a Content Security Policy that disallows inline scripts to reduce the impact of stored XSS payloads
Configure a WAF to inspect and block script payloads submitted to WordPress plugin settings endpoints

bash

# Example Content Security Policy header for nginx to mitigate stored XSS
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self';" always;