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Jonathan Pimperton
Jonathan Pimperton

Posted on • Originally published at sitevett.com

Is Your jQuery Version a Security Risk?

#webdev #security #javascript #wordpress

Is Your jQuery Version a Security Risk?

WordPress, by default, includes a version of jQuery. This is great for developers because it means we don't have to worry about manually enqueueing it for most projects. However, there's a common pitfall: many themes and plugins bundle their own copy of jQuery. If this bundled version is outdated, it can introduce serious security vulnerabilities. Specifically, jQuery versions prior to 3.5.0 are known to have cross-site scripting (XSS) vulnerabilities, identified by CVE-2020-11022 and CVE-2020-11023. These issues could allow an attacker to inject malicious code into your site.

How to Check Your jQuery Version

The first step is to determine which version of jQuery your website is actually using. The easiest way to do this is by inspecting the page source.

  1. View Page Source: In your web browser, right-click anywhere on your website's frontend and select "View Page Source" or "Inspect Element".

  2. Search for jQuery: Once the source code is displayed, search for "jquery". You're looking for a <script> tag that loads the jQuery library. It will typically look something like this:

    <script src="https://example.com/wp-content/plugins/some-plugin/assets/js/jquery-1.12.4.min.js"></script>

    or

    <script src="https://example.com/wp-content/themes/your-theme/js/jquery-3.3.1.min.js"></script>

    The filename will clearly indicate the version. If you see a version number like 1.x.x, 2.x.x, or 3.0.0 through 3.4.x, you are likely vulnerable. WordPress itself ships with a secure version of jQuery, typically loaded from wp-includes/js/jquery/jquery.js or a similar path within the core WordPress files. If your site is only loading jQuery from this core path, you're probably fine. The problem arises when a theme or plugin loads its own version, often an older one.

Fixing Vulnerable jQuery Versions

Once you've identified an outdated jQuery version, you have a few practical options to address it.

1. Update Your Theme or Plugin

The most straightforward solution is to update the theme or plugin that's bundling the vulnerable jQuery version. Developers are aware of these vulnerabilities and have likely released updates that use a secure, modern version of jQuery or have removed the bundled copy altogether.

  • Action: Navigate to your WordPress dashboard, go to "Appearance" > "Themes" or "Plugins" > "Installed Plugins". Check for available updates for your active theme and any plugins. Apply them if they are available.

If updating is not an immediate option, or if the theme/plugin developer hasn't provided a fix, you'll need to take a more direct approach.

2. Dequeue the Vulnerable Script

WordPress provides functions to control how scripts are enqueued and dequeued. You can use wp_dequeue_script to remove the problematic, bundled jQuery from being loaded and ensure that the secure version provided by WordPress is used instead.

This is typically done in your theme's functions.php file or within a custom plugin. You need to know the handle that the vulnerable script was registered with. Often, themes and plugins will register their jQuery with a distinct handle. If they don't, it can be trickier, but usually, the script path itself can help you infer potential handles.

Here's an example of how you might dequeue a script. Let's assume the vulnerable script was registered with the handle 'old-jquery' and loaded from a path like /wp-content/themes/my-theme/js/jquery-1.10.2.min.js.

<?php
/**
 * Dequeue vulnerable jQuery version and ensure WordPress core version is used.
 */
function my_dequeue_vulnerable_jquery() {
    // Check if the script handle is registered.
    // The handle 'old-jquery' is an example; you'll need to find the actual handle.
    // If the handle is not known, you might need to inspect the source or plugin/theme code.
    if ( wp_script_is( 'old-jquery', 'registered' ) ) {
        wp_dequeue_script( 'old-jquery' );
        // Optionally, you can also de-register it to prevent it from being re-enqueued.
        // wp_deregister_script( 'old-jquery' );
    }

    // Ensure WordPress core jQuery is enqueued if it's not already.
    // This is generally handled automatically by WordPress, but can be explicit.
    // wp_enqueue_script( 'jquery' );
}
add_action( 'wp_enqueue_scripts', 'my_dequeue_vulnerable_jquery', 999 );
?>
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Finding the Script Handle: This is the most challenging part of this method. If you can't find the handle by inspecting the theme/plugin's code directly, you might need to resort to some detective work. Sometimes the handle is close to the filename, or it's a common convention like jquery-custom or the plugin slug. If all else fails, you might have to look for the wp_enqueue_script() call within the theme or plugin's PHP files.

3. Migrate to Vanilla JavaScript

For new development or significant refactors, consider migrating away from jQuery entirely and using modern, vanilla JavaScript. Modern browsers have excellent support for features that jQuery abstracted, and the performance benefits can be significant. This is a more involved process but eliminates the dependency on jQuery versions and their associated vulnerabilities.

  • Action: Identify the jQuery-dependent functionality in your theme or plugin. Rewrite these functionalities using native JavaScript APIs. For example, replacing $(selector).hide() with document.querySelector(selector).style.display = 'none';.

By taking these steps, you can ensure your WordPress site is not compromised by outdated jQuery libraries, keeping your visitors and your data secure.

SiteVett checks this automatically as part of a free website QA scan with 60+ checks across security, SEO, content, performance, and more.

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