CVE-2026-5670: Student Management System RCE Vulnerability

CVE-2026-5670 Overview

A critical unrestricted file upload vulnerability has been identified in the Cyber-III Student-Management-System. This vulnerability affects the move_uploaded_file function within the /AssignmentSection/submission/upload.php file, allowing attackers to upload arbitrary files without proper validation. The vulnerability can be exploited remotely by authenticated users, potentially enabling execution of malicious code on the target server.

Critical Impact

Remote attackers can exploit this unrestricted file upload vulnerability to upload malicious files, potentially leading to remote code execution, server compromise, and unauthorized access to sensitive student data.

Affected Products

• Cyber-III Student-Management-System (all versions up to commit 1a938fa61e9f735078e9b291d2e6215b4942af3f)
• Rolling release deployment models without versioned releases

Discovery Timeline

• April 6, 2026 - CVE-2026-5670 published to NVD
• April 7, 2026 - Last updated in NVD database

Technical Details for CVE-2026-5670

Vulnerability Analysis

This vulnerability stems from improper access control (CWE-284) in the file upload functionality of the Student-Management-System. The move_uploaded_file function in /AssignmentSection/submission/upload.php fails to properly validate the type, content, or extension of uploaded files. This allows an authenticated attacker to bypass intended file type restrictions and upload arbitrary files to the server.

The vulnerability is network-exploitable, requiring low privileges and no user interaction. An attacker who successfully exploits this vulnerability could upload web shells, malicious scripts, or other dangerous content that could lead to complete server compromise. The exploit has been publicly disclosed, increasing the risk of active exploitation.

Root Cause

The root cause of this vulnerability is improper input validation and access control on the file upload mechanism. The upload.php script does not implement adequate checks on the File argument before passing it to move_uploaded_file, allowing attackers to manipulate the uploaded file content and potentially execute arbitrary code on the server.

Key deficiencies include:

• Lack of file type validation (MIME type checking)
• Missing file extension whitelist enforcement
• Absence of content inspection for malicious payloads
• Insufficient access control on the upload endpoint

Attack Vector

The attack can be initiated remotely over the network by any authenticated user with access to the assignment submission functionality. An attacker would craft a malicious HTTP request containing a dangerous file (such as a PHP web shell) disguised or uploaded directly to the vulnerable endpoint.

The exploitation mechanism involves:

1. An authenticated attacker accesses the /AssignmentSection/submission/upload.php endpoint
2. The attacker submits a malicious file through the File parameter
3. The server accepts the file without proper validation due to missing input sanitization
4. The malicious file is stored on the server and can be accessed directly
5. Execution of the uploaded file grants the attacker remote code execution capabilities

For technical details on the vulnerability, see the GitHub Issue #241 and the VulDB entry.

Detection Methods for CVE-2026-5670

Indicators of Compromise

• Suspicious file uploads to /AssignmentSection/submission/ directory with executable extensions (.php, .phtml, .phar)
• Web shell files appearing in upload directories
• Unusual outbound network connections from the web server
• Unexpected process execution originating from the web application user

Detection Strategies

• Monitor web server access logs for POST requests to /AssignmentSection/submission/upload.php with unusual file types
• Implement file integrity monitoring on upload directories to detect unauthorized file additions
• Deploy web application firewall (WAF) rules to block uploads of executable file types
• Use endpoint detection and response (EDR) solutions to monitor for web shell activity

Monitoring Recommendations

• Enable verbose logging for the assignment submission module
• Configure alerts for any executable file creation in web-accessible directories
• Monitor for PHP process spawning unexpected child processes
• Review uploaded files periodically for suspicious content or naming patterns

How to Mitigate CVE-2026-5670

Immediate Actions Required

• Restrict access to the /AssignmentSection/submission/upload.php endpoint until a patch is available
• Implement server-side file type validation and extension whitelisting
• Remove or quarantine any suspicious files already present in upload directories
• Consider temporarily disabling the file upload functionality if not critical to operations

Patch Information

The Cyber-III Student-Management-System uses continuous delivery with rolling releases, meaning no versioned patches are available. The project maintainers were informed of the vulnerability through GitHub Issue #241 but have not yet responded. Users should monitor the project repository for updates and apply any commits that address the file upload validation issue.

Workarounds

• Implement a web application firewall (WAF) rule to block uploads of potentially dangerous file types
• Add server-side validation to check file MIME types and extensions before processing
• Configure the web server to prevent execution of uploaded files by disabling PHP processing in upload directories
• Implement file content scanning for malicious payloads before accepting uploads

# Apache configuration to disable PHP execution in upload directory
# Add to .htaccess in /AssignmentSection/submission/
<Directory "/var/www/html/AssignmentSection/submission/">
    php_admin_flag engine off
    AddHandler default-handler .php .phtml .phar
</Directory>