Chamilo is a popular open-source learning management system (LMS) used by educational institutions and businesses worldwide. Recently, a critical cross-site scripting (XSS) vulnerability (CVE-2023-34961) has been discovered in Chamilo versions v1.11.x up to v1.11.18. This vulnerability, specifically found in the /feedback/comment field, could allow attackers to execute arbitrary code, steal sensitive user data, or even take control of the affected website.

In this post, we'll discuss the details of this vulnerability, how it can be exploited, and recommended mitigation steps that you should take if you're using a vulnerable version of Chamilo.

Exploit Details

The vulnerability exists in the /feedback/comment field used by Chamilo to send user feedback and comments to the website administrators. When a user submits a comment, it is possible to include malicious JavaScript code in the comment text. If this input isn't adequately sanitized and treated as raw HTML when displayed to other users or administrators, the code will execute in the user's browser.

The following code snippet demonstrates the vulnerability

<!-- Example of an XSS payload in the /feedback/comment field -->
<script> alert('XSS Vulnerability'); </script>

When a user views a page containing the malicious script, the alert will display, indicating that the XSS attack was successful. A more advanced payload could be used to steal user data or control the user's account.

Original References

The Chamilo project has acknowledged this vulnerability in their official security advisory, which can be found at the following link:

- Chamilo Security Advisory for CVE-2023-34961

Additionally, the Common Vulnerabilities and Exposures (CVE) database also provides information on this vulnerability:

- CVE-2023-34961 - Chamilo v1.11.x up to v1.11.18 Cross-Site Scripting (XSS) Vulnerability

Mitigation Steps

To protect your Chamilo installation against this vulnerability, it is highly recommended to update to the latest version (v1.11.19 or later). The update contains a patch that properly sanitizes user input, preventing arbitrary code execution.

You can follow these steps to update your Chamilo installation

1. Visit the Chamilo GitHub repository and find the latest release: Chamilo GitHub Releases

2. Download the latest release package and follow the provided update instructions.

3. After updating, verify that the vulnerability is no longer present by testing the /feedback/comment field with a harmless payload (e.g., <script> alert('Test'); </script>). If the alert doesn't display, your installation is no longer vulnerable.


Cross-site scripting (XSS) vulnerabilities, like the one found in Chamilo v1.11.x up to v1.11.18 (CVE-2023-34961), pose a significant risk to both users and website administrators. By staying vigilant and ensuring that you're using the latest version of software, you can protect your website and users from the potential harm caused by attackers exploiting such vulnerabilities.


Published on: 06/08/2023 19:15:00 UTC
Last modified on: 06/15/2023 18:57:00 UTC