CVE-2026-22241: Open eClass Platform RCE Vulnerability

CVE-2026-22241 Overview

CVE-2026-22241 is an arbitrary file upload vulnerability affecting the Open eClass platform (formerly known as GUnet eClass), a widely-used course management system in educational institutions. The vulnerability exists in the theme import functionality and allows attackers with administrative privileges to upload arbitrary files to the server's file system. Due to the lack of validation or sanitization of files present inside uploaded zip archives, this flaw can be exploited to achieve remote code execution on the web server.

Critical Impact

Successful exploitation enables authenticated administrators to upload malicious files, including web shells or backdoors, leading to complete server compromise and remote code execution.

Affected Products

• Open eClass platform versions prior to 4.2
• GUnet eClass (legacy naming) versions prior to 4.2

Discovery Timeline

• 2026-01-08 - CVE-2026-22241 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2026-22241

Vulnerability Analysis

This vulnerability is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type). The flaw resides in the theme import functionality within the administrative interface of Open eClass. When an administrator uploads a theme package as a zip archive, the application fails to properly validate or sanitize the contents of the archive before extraction.

The exploitation requires network access and administrative privileges on the Open eClass platform. While this limits the attack surface to authenticated administrators, compromised admin credentials or insider threats could leverage this vulnerability for complete server takeover. The impact spans full compromise of confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause of CVE-2026-22241 is the absence of file validation and sanitization mechanisms when processing uploaded zip archives in the theme import feature. The application extracts all files from the uploaded archive without checking file types, extensions, or content, allowing arbitrary files—including executable PHP scripts—to be placed on the server's file system.

Attack Vector

An attacker with administrative access to the Open eClass platform can exploit this vulnerability by:

1. Crafting a malicious zip archive containing a PHP web shell or other executable payload
2. Navigating to the theme import functionality in the admin panel
3. Uploading the crafted zip archive as a "theme package"
4. The server extracts the archive without validation, placing the malicious file in an accessible location
5. Accessing the uploaded malicious file directly via HTTP to execute arbitrary code

The following patch from modules/admin/theme_options.php addresses the vulnerability by implementing proper sanitization:

                 "" => array('fluidContainerWidth','maxHeightJumbotron','maxWidthTextJumbotron', 'sliderWidthImgForm')
             );
 $active_theme = get_config('theme_options_id');
-$preview_theme = isset($_SESSION['theme_options_id']) ? $_SESSION['theme_options_id'] : NULL;
-$theme_id = isset($preview_theme) ? $preview_theme : $active_theme;
+$preview_theme = $_SESSION['theme_options_id'] ?? NULL;
+$theme_id = $preview_theme ?? $active_theme;
 if (isset($_GET['reset_theme_options'])) {
     unset($_SESSION['theme_options_id']);
     redirect_to_home_page('modules/admin/theme_options.php');

Source: GitHub Commit Update

Detection Methods for CVE-2026-22241

Indicators of Compromise

• Unexpected PHP files or web shells appearing in theme directories or upload paths
• Suspicious HTTP requests targeting newly created files in theme-related directories
• Administrative activity related to theme imports from unusual IP addresses or at unusual times
• Server logs showing execution of unfamiliar PHP scripts in web-accessible directories

Detection Strategies

• Monitor file system changes in Open eClass theme directories for unauthorized file creation
• Implement web application firewall (WAF) rules to detect and block uploads containing executable file types
• Review administrative audit logs for theme import activities and correlate with expected maintenance windows
• Deploy file integrity monitoring on the Open eClass installation directory

Monitoring Recommendations

• Enable verbose logging for the Open eClass administrative interface
• Set up alerts for new file creation events in the themes and upload directories
• Monitor outbound network connections from the web server for signs of reverse shell activity
• Implement SIEM correlation rules to detect file upload followed by immediate HTTP access to new files

How to Mitigate CVE-2026-22241

Immediate Actions Required

• Upgrade Open eClass to version 4.2 or later immediately
• Audit all existing files in theme directories for unauthorized or suspicious content
• Review administrative access logs for any recent theme import activities
• Restrict administrative access to trusted users and implement multi-factor authentication

Patch Information

The vulnerability has been addressed in Open eClass version 4.2. The fix implements proper validation and sanitization of files within uploaded zip archives during theme imports. Organizations should upgrade to version 4.2 or later by applying the security patch referenced in commit 3f9d267b79812a4dd708bb1302339e6a5abe67d9. For detailed information, refer to the GitHub Security Advisory GHSA-rf6j-xgqp-wjxg.

Workarounds

• Disable the theme import functionality in the administrative panel until patching is possible
• Implement network-level access controls to restrict administrative panel access to trusted IP ranges
• Configure the web server to deny execution of PHP files in theme upload directories
• Deploy a web application firewall with rules blocking zip file uploads containing PHP files

# Example: Disable PHP execution in theme upload directory (Apache)
<Directory /var/www/openeclass/themes/uploads>
    php_admin_flag engine off
    <FilesMatch "\.php$">
        Require all denied
    </FilesMatch>
</Directory>