CVE-2025-14028: WordPress Contact Form Plugin XSS Flaw

CVE-2025-14028 Overview

The Contact Us Simple Form plugin for WordPress is vulnerable to Stored Cross-Site Scripting (XSS) via admin settings in all versions up to, and including, 1.0. This vulnerability stems from insufficient input sanitization and output escaping on user-supplied attributes, allowing authenticated attackers with administrator-level access to inject arbitrary web scripts into pages. These malicious scripts execute whenever any user accesses an injected page.

Critical Impact

Authenticated attackers with administrator privileges can inject persistent malicious scripts that execute in the browsers of all users who access the affected pages, potentially leading to session hijacking, credential theft, or malware distribution.

Affected Products

• Contact Us Simple Form WordPress Plugin version 1.0 and earlier
• WordPress installations running the vulnerable plugin versions

Discovery Timeline

• 2026-01-07 - CVE-2025-14028 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2025-14028

Vulnerability Analysis

This Stored Cross-Site Scripting vulnerability exists within the admin settings functionality of the Contact Us Simple Form plugin. The plugin fails to properly sanitize user-supplied input before storing it in the database and fails to escape output when rendering these values on the page. While the attack requires administrator-level authentication, the vulnerability is classified as Stored XSS, meaning the malicious payload persists in the database and affects all users who subsequently access pages containing the injected content.

The vulnerability is particularly concerning in multi-administrator WordPress environments where a compromised or malicious administrator account could inject scripts that persist and affect other administrators, potentially leading to privilege persistence or cross-administrator attacks.

Root Cause

The root cause of this vulnerability is improper input validation and output encoding within the plugin code. According to the WordPress Plugin Code Line 223 and WordPress Plugin Code Line 239, the plugin accepts user-supplied attributes without sufficient sanitization using WordPress escaping functions such as esc_html(), esc_attr(), or wp_kses(). This allows malicious JavaScript code to be stored and subsequently rendered in the browser context of users viewing affected pages.

Attack Vector

The attack is network-based but requires high privileges (administrator-level access) to exploit. An attacker must first authenticate with administrator credentials and then navigate to the plugin's admin settings page. From there, they can inject malicious JavaScript payloads into vulnerable form fields. Once saved, these payloads are stored in the WordPress database and executed whenever any user—including other administrators or site visitors—accesses a page that renders the injected content.

The vulnerability mechanism involves insufficient sanitization in the admin settings processing. The plugin stores user input directly without proper escaping, and when the stored values are rendered in HTML output, the malicious script payload executes in the victim's browser context. For detailed technical analysis, see the Wordfence Vulnerability Analysis.

Detection Methods for CVE-2025-14028

Indicators of Compromise

• Unusual JavaScript code embedded within Contact Us Simple Form plugin settings in the WordPress database
• Unexpected script tags or event handlers in the wp_options table entries related to the plugin
• Browser security warnings or Content Security Policy (CSP) violations on pages containing the contact form
• Reports from users about unexpected behavior or redirects when viewing pages with the contact form

Detection Strategies

• Review WordPress database entries for the Contact Us Simple Form plugin for suspicious script content or encoded payloads
• Monitor WordPress admin activity logs for unusual changes to plugin settings, particularly from unexpected IP addresses
• Implement Web Application Firewall (WAF) rules to detect XSS patterns in HTTP POST requests to the plugin's admin pages
• Use automated security scanning tools like Wordfence or Sucuri to identify XSS vulnerabilities in installed plugins

Monitoring Recommendations

• Enable WordPress audit logging to track all changes to plugin settings and configuration
• Configure Content Security Policy headers to prevent inline script execution and report violations
• Deploy endpoint detection and response (EDR) solutions like SentinelOne to monitor for suspicious browser-based attacks
• Regularly review administrator account activity and access patterns for anomalies

How to Mitigate CVE-2025-14028

Immediate Actions Required

• Update the Contact Us Simple Form plugin to a patched version when available from the WordPress plugin repository
• Review current plugin settings for any suspicious or unexpected script content and remove any malicious entries
• Audit administrator accounts for any unauthorized access or compromised credentials
• Consider temporarily disabling the plugin until a patch is released if the risk is unacceptable

Patch Information

At the time of publication, users should monitor the WordPress Plugin Repository for updated versions that address this vulnerability. The fix should implement proper input sanitization using WordPress security functions such as sanitize_text_field() and output escaping using esc_html() or esc_attr() where appropriate.

Workarounds

• Implement strict Content Security Policy (CSP) headers to prevent execution of inline scripts on your WordPress site
• Limit administrator account access to trusted users only and enforce strong authentication practices including two-factor authentication
• Deploy a Web Application Firewall (WAF) with XSS protection rules to filter malicious payloads before they reach the application
• Consider using alternative contact form plugins that have undergone security audits until this vulnerability is patched

# Add Content Security Policy headers in .htaccess for Apache
# This helps mitigate XSS attacks by restricting script sources
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';"