CVE-2025-3638: Critical CSRF Vulnerability in Moodle’s Brickfield Tool

Overview

In the ever-evolving digital realm, cybersecurity vulnerabilities can have far-reaching impacts, particularly when they involve widely used e-learning platforms like Moodle. This blog post focuses on a recently discovered critical vulnerability, CVE-2025-3638, affecting Moodle’s Brickfield tool. This vulnerability is a Cross-Site Request Forgery (CSRF) risk, a threat that enables attackers to trick victims into executing actions of the attacker’s choosing.
Given the severity of this vulnerability, it is imperative for organizations using Moodle to understand its potential implications and take immediate steps to mitigate the risks.

Vulnerability Summary

CVE ID: CVE-2025-3638
Severity: Critical (8.8 CVSS Severity Score)
Attack Vector: Web
Privileges Required: Low
User Interaction: Required
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

Moodle | Versions using Brickfield tool

How the Exploit Works

The vulnerability exists because the analysis request action in Moodle’s Brickfield tool lacks a necessary token, which would typically be used to prevent CSRF attacks. This missing token creates a loophole for attackers, enabling them to deceive users into executing unwanted actions in their sessions.
By exploiting this vulnerability, an attacker can generate a malicious link or script that, when clicked or executed by the victim, performs actions on their behalf without their knowledge or consent. This could potentially lead to system compromise or data leakage, depending on the level of access the victim has.

Conceptual Example Code

Here is a conceptual example illustrating how the vulnerability might be exploited:

POST /brickfield/analysis_request HTTP/1.1
Host: victim.example.com
Content-Type: application/x-www-form-urlencoded
user_session_id=12345&malicious_action=drop_all_tables

In this example, an attacker could craft a malicious POST request to the analysis_request endpoint of the Brickfield tool. The request contains a user_session_id and a malicious_action – in this case, ‘drop_all_tables’. If the victim unknowingly executes this request, it could lead to a system compromise.

Mitigation Guidance

To mitigate this vulnerability, users are advised to apply the vendor-supplied patch as soon as possible. If applying the patch is not immediately feasible, using a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can serve as temporary mitigation measures. These systems can block or alert on suspicious requests, thereby providing a line of defense against potential exploits.
As always, users should exercise caution when clicking on links or executing actions, particularly if they originate from untrusted sources. Regular security training can help to raise awareness of such threats among users.