CVE-2022-50939: e107 CMS Path Traversal Vulnerability

CVE-2022-50939 Overview

e107 CMS version 3.2.1 contains a critical file upload vulnerability that allows authenticated administrators to override arbitrary server files through path traversal. The vulnerability exists in the Media Manager's remote URL upload functionality (image.php) where the upload_caption parameter is not properly sanitized. An attacker with administrative privileges can use directory traversal sequences (../../../) in the upload_caption field to overwrite critical system files outside the intended upload directory. This can lead to complete compromise of the web application by overwriting configuration files, executable scripts, or other critical system components.

Critical Impact

Authenticated administrators can leverage path traversal to overwrite arbitrary files on the server, potentially leading to complete system compromise through modification of configuration files or injection of malicious code.

Affected Products

• e107 CMS version 3.2.1
• e107 CMS Media Manager (image.php component)
• e107 CMS Admin Interface

Discovery Timeline

• 2026-01-13 - CVE CVE-2022-50939 published to NVD
• 2026-01-13 - Last updated in NVD database

Technical Details for CVE-2022-50939

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), commonly known as Path Traversal or Directory Traversal. The flaw resides in the image.php component within e107 CMS's admin interface, specifically in the Media Manager's remote URL upload functionality.

The core issue stems from insufficient input validation on the upload_caption parameter. When an authenticated administrator uploads an image via a remote URL, the application fails to properly sanitize the caption field, allowing attackers to inject directory traversal sequences. This enables file writes to locations outside the designated upload directory.

Successful exploitation allows an attacker to overwrite critical application files such as configuration files (potentially exposing database credentials or enabling further attacks), PHP scripts (enabling remote code execution), or .htaccess files (modifying server behavior). While the attack requires administrative privileges, compromised admin accounts or social engineering scenarios could enable this attack vector.

Root Cause

The root cause lies in improper input validation within the image.php component. The upload_caption parameter accepts user-supplied input that is subsequently used in file path construction without adequate sanitization. The application fails to strip or properly encode directory traversal sequences such as ../ before incorporating the value into file system operations.

The lack of a security control to canonicalize paths or restrict file operations to a specific directory tree allows attackers to escape the intended upload directory and write to arbitrary locations on the file system accessible by the web server process.

Attack Vector

The attack is network-based and requires authentication with administrative privileges. The attacker must have access to the e107 CMS admin panel and specifically the Media Manager functionality. By crafting a malicious request to the image.php endpoint with path traversal sequences in the upload_caption parameter, an attacker can control where uploaded files are written on the server.

The exploitation workflow involves:

1. Authenticating to the e107 CMS admin panel with administrator credentials
2. Navigating to the Media Manager's remote URL upload functionality
3. Submitting a crafted request with directory traversal sequences in the upload_caption field
4. The server processes the request and writes the uploaded content to an attacker-controlled path

For technical details on exploitation, refer to the Exploit-DB entry #50910 and the VulnCheck Advisory.

Detection Methods for CVE-2022-50939

Indicators of Compromise

• Unexpected modifications to critical system files such as e107_config.php, .htaccess, or PHP scripts in core directories
• Web server access logs showing requests to image.php with unusual or encoded upload_caption parameter values containing ../ sequences
• File system audit logs indicating file writes outside the designated media upload directories
• Unexpected PHP files appearing in web root or configuration directories

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block path traversal patterns in HTTP request parameters
• Monitor access logs for requests to /e107_admin/image.php containing URL-encoded or plain directory traversal sequences
• Deploy file integrity monitoring (FIM) on critical application files and configuration directories
• Review administrative user activity logs for unusual Media Manager operations

Monitoring Recommendations

• Enable detailed logging for the e107 CMS admin interface and regularly audit administrative actions
• Configure real-time alerts for file modifications in critical directories such as the web root and configuration folders
• Implement anomaly detection for administrator account behavior to identify potential account compromise
• Monitor for creation of new PHP files in unexpected directories

How to Mitigate CVE-2022-50939

Immediate Actions Required

• Audit administrator accounts and ensure only trusted personnel have administrative access
• Review file system for unauthorized modifications to critical configuration files and PHP scripts
• Implement additional access controls on the admin interface such as IP whitelisting or multi-factor authentication
• Consider temporarily restricting access to the Media Manager functionality until a patch is applied

Patch Information

Users should check the e107 Official Website and e107 Download Page for updated versions that address this vulnerability. Upgrading to the latest patched version is the recommended remediation approach.

Review the VulnCheck Advisory for additional vendor guidance and patch status.

Workarounds

• Implement strict input validation at the web server or WAF level to block requests containing path traversal sequences in POST parameters
• Restrict administrative access to the e107 CMS admin panel using IP whitelisting or VPN-only access
• Apply the principle of least privilege by running the web server process with minimal file system permissions
• Consider disabling the remote URL upload functionality in Media Manager if not required for business operations

# Example: Apache mod_security rule to block path traversal attempts
# Add to Apache configuration or .htaccess (if mod_security is available)
SecRule ARGS "@contains ../" "id:100001,phase:2,deny,status:403,msg:'Path traversal attempt detected'"

# Example: Restrict admin access by IP in Apache
<Directory "/var/www/html/e107_admin">
    Require ip 192.168.1.0/24
</Directory>