CVE-2025-6740: Contact Form 7 Database Addon XSS Flaw

CVE-2025-6740 Overview

CVE-2025-6740 is a Stored Cross-Site Scripting (XSS) vulnerability in the Contact Form 7 Database Addon (contact-form-cfdb7) plugin for WordPress. The flaw affects all versions up to and including 1.3.1 and stems from insufficient input sanitization and output escaping on the tmpD parameter. Unauthenticated attackers can inject arbitrary web scripts that execute when a user accesses an affected page. The issue is tracked under CWE-79 and was published to the National Vulnerability Database (NVD) on July 4, 2025.

Critical Impact
Unauthenticated attackers can store JavaScript payloads that execute in the browser context of any user visiting an injected page, enabling session theft, credential harvesting, and administrative account takeover.

Affected Products

Ciphercoin Contact Form 7 Database Addon (contact-form-cfdb7) WordPress plugin, versions * through 1.3.1
WordPress sites running the vulnerable plugin with public-facing forms
Any downstream site or environment embedding the affected plugin

Discovery Timeline

2025-07-04 - CVE-2025-6740 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-6740

Vulnerability Analysis

The vulnerability resides in the Contact Form 7 Database Addon plugin, which stores form submissions from the Contact Form 7 plugin for later review by site administrators. The tmpD request parameter is processed and later rendered without adequate sanitization or output escaping. An attacker can submit crafted input containing HTML or JavaScript payloads. When an administrator or other authorized user opens a page that renders the stored value, the browser executes the injected script in the site's origin.

Because the injection is stored server-side, the payload persists across sessions and executes on every page load until the record is removed. Exploitation requires user interaction — a victim must access a page that renders the malicious content — but no authentication is required to submit the payload.

Root Cause

The root cause is a failure to apply WordPress sanitization helpers such as sanitize_text_field() on input and escaping helpers such as esc_html() or esc_attr() on output for the tmpD parameter. This maps to CWE-79: Improper Neutralization of Input During Web Page Generation. The upstream fix is documented in WordPress Change Set 3320134.

Attack Vector

The attack vector is network-based and requires no privileges. An attacker sends a crafted HTTP request that includes a malicious payload in the tmpD parameter. The payload is stored in the plugin's database records. When an administrator later views the affected admin screen or a rendered page, the script executes in their browser session. Consult the plugin source and Wordfence Vulnerability Intel for parameter handling details.

Detection Methods for CVE-2025-6740

Indicators of Compromise

HTTP POST requests to plugin endpoints containing tmpD values with <script>, onerror=, onload=, or javascript: sequences
Database rows within the plugin's storage tables containing HTML tags or JavaScript event handlers in fields that should contain plain text
Unexpected outbound requests from administrator browsers to attacker-controlled domains following access to the plugin's admin screens
New or modified WordPress administrator accounts created shortly after admin sessions that viewed submitted form data

Detection Strategies

Inspect web server access logs for anomalous payload characters in the tmpD parameter, including URL-encoded %3Cscript%3E and event handler patterns
Query the plugin's database tables for stored values containing angle brackets or common XSS keywords
Deploy a Web Application Firewall (WAF) rule that flags requests targeting the Contact Form 7 Database Addon endpoints with script-like payloads

Monitoring Recommendations

Enable WordPress audit logging to capture form submission and admin page access events
Alert on the creation of new administrator accounts or modification of user roles following exposure to submitted form data
Monitor browser telemetry from administrative workstations for connections to unfamiliar external domains during WordPress admin sessions

How to Mitigate CVE-2025-6740

Immediate Actions Required

Update the Contact Form 7 Database Addon plugin to the fixed release published after version 1.3.1 per WordPress Change Set 3320134
Audit stored form submissions for records containing HTML tags or JavaScript and purge malicious entries
Rotate credentials and session tokens for any administrator who accessed the plugin's admin screens before patching

Patch Information

The vendor addressed the vulnerability in the code committed under WordPress Change Set 3320134. Site administrators should upgrade to the latest available version listed on the plugin page. Confirm the installed version through the WordPress Plugins admin panel after the update.

Workarounds

Deactivate and remove the Contact Form 7 Database Addon plugin until the patched version is applied
Restrict access to plugin admin pages using IP allowlisting at the web server or WAF layer
Deploy a Content Security Policy (CSP) that blocks inline scripts to reduce the impact of stored XSS payloads
Add a WAF rule that rejects requests where tmpD contains <, >, or common event handler substrings

bash

# Example WP-CLI commands to update or remove the vulnerable plugin
wp plugin update contact-form-cfdb7
wp plugin deactivate contact-form-cfdb7
wp plugin delete contact-form-cfdb7