DOMPurify is a fast, efficient, and widely used XSS sanitizer that works with HTML, MathML, and SVG. It helps ensure that web applications stay secure and safe from cross-site scripting attacks, which are among the most common security vulnerabilities found on the internet today. However, sometimes even a popular sanitizer like DOMPurify can have a weakness, and in this case, it's the CVE-2024-47875 vulnerability.

Exploit Details

This vulnerability, which has been designated with the CVE number CVE-2024-47875, concerns the DOMPurify library's inability to handle nesting-based mXSS (mutation-based cross-site scripting) attacks. This weakness can be exploited by attackers to bypass the sanitizer's security mechanisms, potentially allowing malicious JavaScript code to be executed.

This issue was discovered, reported, and subsequently fixed in DOMPurify versions 2.5. and 3.1.3. It's essential that web developers using DOMPurify update their libraries to one of these versions or a later release to ensure the vulnerability is patched.

To give you a better understanding of the vulnerability, here's a code snippet illustrating the exploit:

<!DOCTYPE html>
<html>
  <head>
    <script src="path/to/dompurify.js"></script>
  </head>
  <body>
    <script>
      const payload =
        &lt;a&gt;&lt;!--\u0068\U00000068\uff48\u0251\u_AB8E\uFFF7\u05db\u00de\u0099emics--&gt;&lt;img src=x onerror=alert(1)&gt;;

      const clean = DOMPurify.sanitize(payload);
      document.write(clean);
    </script>
  </body>
</html>

In this example, we are using DOMPurify to sanitize the 'payload' variable, which contains an mXSS attack. However, due to the vulnerability, the sanitizer is not able to parse and filter the malicious content correctly, leading to the successful execution of the embedded onerror event handler in the img tag.

For more information about the vulnerability, its impact, and the investigation that led to its discovery, please refer to the following resources:

1. GitHub Issue: DOMPurify Issue #543 – This is the official issue report on DOMPurify's project repository. It provides detailed information about the vulnerability and its exploitation.
2. DOMPurify Release Notes: DOMPurify v2.5. and DOMPurify v3.1.3 – These release notes document the changes made in each version of the library and confirm the resolutions applied for the CVE-2024-47875 vulnerability.
3. CVE Details: CVE-2024-47875 – This page provides the official CVE entry for the vulnerability, including a brief summary, affected versions, and links to relevant documentation.

Conclusion

Security vulnerabilities like the CVE-2024-47875 in DOMPurify highlight the importance of continuous updates and regular patching for web applications and libraries. As attackers evolve their strategies and find new ways to exploit even the most established security solutions, developers must stay vigilant in monitoring for and addressing potential vulnerabilities. By updating DOMPurify to the latest version, you can help ensure your web application remains safe from XSS attacks and other threats.

Timeline

Published on: 10/11/2024 15:15:05 UTC
Last modified on: 10/15/2024 12:58:51 UTC