WordPress has become the backbone of millions of websites, and plugins are its lifeblood. One of the most widely adopted contact form solutions is “Contact Form Plugin – Fastest Contact Form Builder Plugin for WordPress by Fluent Forms" (commonly known as WordPress Fluent Forms), published by WPManageNinja LLC. But in early 2023, security researchers discovered a serious vulnerability: CVE-2023-24410, an SQL Injection flaw that can potentially allow attackers to gain unauthorized access to your website’s database.

In this post, we'll break down what this vulnerability means, how it can be exploited, show you a simple code snippet demonstrating the issue, and provide guidance for mitigation. We’ll use plain language, making this problem clear for website owners, developers, and anyone who cares about WordPress security.

CVE: CVE-2023-24410

- Vulnerable Plugin: Fluent Forms (Contact Form Plugin – Fastest Contact Form Builder Plugin for WordPress by Fluent Forms)

Versions Affected: All versions through 4.3.25

- Plugin URL: Fluent Forms on WordPress.org
- Vulnerability Type: Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
- Discovered by: Security community, tracked on CVE Details
- Patched in: Later versions (check plugin’s changelog)

What’s the Issue?

Fluent Forms is popular for building forms on WordPress. Versions through 4.3.25 didn’t properly sanitize user input before putting it into SQL queries. This lets hackers inject malicious code right into the site’s database commands.

Technical Explanation: How SQL Injection Works Here

SQL Injection happens when user-supplied data isn't filtered or sanitized before being used in a database query. An attacker can submit specially crafted form fields, which the plugin passes directly to the database server. If the plugin doesn’t clean up these inputs, the database executes them as code.

Here’s a simplified example. Imagine this is part of a form submission handler in PHP

// Pseudocode / simplified vulnerable pattern
$user_name = $_POST['name'];

// Dangerous SQL query: direct user input
$sql = "SELECT * FROM wp_users WHERE name = '$user_name'";
$result = $wpdb->get_results($sql);

If $user_name is not sanitized, an attacker could submit the form with this value

admin' OR '1'='1

The resulting SQL becomes

SELECT * FROM wp_users WHERE name = 'admin' OR '1'='1'

Which will always return data, potentially letting an attacker log in as any user, dump database tables, or modify site content.

Proof of Concept (PoC) Exploit

Suppose a vulnerable site has a form built with Fluent Forms where you submit your name and email. An attacker could submit the following:

Field Email: ' OR 1=1; --

By intercepting the form submission (using a browser tool like Burp Suite or directly via curl), an attacker could send something like:

POST /wp-admin/admin-ajax.php?action=fluentform_submit HTTP/1.1
Host: vulnerable-site.com
Content-Type: application/x-www-form-urlencoded

name=test&email=' OR 1=1; --

Depending on how the plugin queries the database, this can mess with data retrieval, leak information, or even let code be executed.

They may create admin accounts, install malware, or redirect your site to phishing pages.

- Typical signs of exploit: Strange admin users, modified posts/pages, unexpected database errors, or your website being blacklisted.

Over 300,000+ sites were at risk because this is one of the most popular contact form plugins.

Update Immediately

Update Fluent Forms to the latest version. Vulnerabilities like these are regularly patched once disclosed.

Review Logs

Check your server and plugin logs for suspicious activity, unusual form entries, or unexpected admin users.

Audit Your Plugins

Always use the Wordfence Vulnerability Database or similar services to ensure your plugins are up-to-date and safe.

Implement a WAF (Web Application Firewall)

Services like Cloudflare or Wordfence Security can block SQL injection attempts.

Least Privilege Principle

Your WordPress database user should have the minimum privileges necessary. Don’t give them DROP, ALTER, or other dangerous permissions.

References

- CVE-2023-24410 on NVD
- Fluent Forms at wordpress.org
- Official Changelog & Security Fixes
- Wordfence Blog: SQL Injection Vulnerabilities in WP Plugins
- Explained: SQL Injection on OWASP

Conclusion

CVE-2023-24410 reminds us that WordPress plugins—even the most popular—can have critical security flaws. SQL Injection is among the most dangerous vulnerabilities, giving attackers a way into the heart of your website. Always keep your plugins up-to-date, monitor for security advisories, and practice good cyber hygiene.

If your site is running Fluent Forms and hasn’t been updated since before February 2023, update right now.

Never underestimate the risk. Protect your website, protect your users.

If you found this post helpful, consider sharing it with your team or fellow site owners. For more in-depth WordPress security tips, follow WPScan’s vulnerability feed. Stay safe!

Timeline

Published on: 10/31/2023 15:15:08 UTC
Last modified on: 11/08/2023 18:44:01 UTC