Drupal 7.x CVE-2011-1938 Path Traversal RCE Analysis and POC

Vulnerability Summary: CVE-2011-1938 (Drupal 7.x Path Traversal Vulnerability) Vulnerability Overview This vulnerability exists in the function within Drupal 7.x, allowing attackers to bypass file extension restrictions by constructing malicious upload requests. This enables the upload and execution of arbitrary files (such as PHP scripts) on the server. Attackers can exploit this vulnerability to achieve remote code execution (RCE), thereby gaining full control over the website server. Affected Scope Affected Versions: Drupal 7.0 to 7.20 (inclusive) Fixed Version: Drupal 7.21 and above Affected Modules: All modules utilizing (e.g., user registration, file upload features) Attack Conditions: - Users can upload files (no login required or only low privileges required) - PHP execution is not disabled on the server (e.g., files can be parsed) - No additional security layers are enabled (e.g., restrictions) Remediation Plan 1. Immediate Upgrade: Upgrade the Drupal core to version 7.21 or higher. 2. Temporary Mitigation Measures (if an immediate upgrade is not possible): - Set the following in : - Configure the web server to prevent execution of files in the upload directory (e.g., Apache ): - Disable related features (e.g., disable user file uploads). 3. Scan Uploaded Files: Scan the directory and delete suspicious files (e.g., , ). Proof of Concept (POC) Code (Exploitation Example) > ⚠️ Note: The above code is intended solely for security research. Unauthorized use to attack others' systems is illegal. Other Key Information Vulnerability ID: CVE-2011-1938 Disclosure Date: May 2011 Severity: High (CVSS Score 9.8) Fix Patch: Fixed in Drupal 7.21 release Related Resources: - Drupal Security Advisory - CVE Details --- ✅ Recommended Action: Immediately upgrade the Drupal core, inspect and clean the upload directory, and strengthen file upload policies.

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Drupal 7.x CVE-2011-1938 Path Traversal RCE Analysis and POC