CVE-2025-70457 Overview
A Remote Code Execution (RCE) vulnerability exists in Sourcecodester Modern Image Gallery App v1.0 within the gallery/upload.php component. The application fails to properly validate uploaded file contents. Additionally, the application preserves the user-supplied file extension during the save process. This allows an unauthenticated attacker to upload arbitrary PHP code by spoofing the MIME type as an image, leading to full system compromise.
Critical Impact
Unauthenticated attackers can achieve full system compromise by uploading malicious PHP files disguised as images, enabling arbitrary code execution on the web server.
Affected Products
- Sourcecodester Modern Image Gallery App v1.0
- PHP-based gallery applications using vulnerable upload.php component
- Systems running the Modern Image Gallery App without proper file upload validation
Discovery Timeline
- 2026-01-23 - CVE CVE-2025-70457 published to NVD
- 2026-01-26 - Last updated in NVD database
Technical Details for CVE-2025-70457
Vulnerability Analysis
This vulnerability is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type). The gallery/upload.php component in Sourcecodester Modern Image Gallery App v1.0 contains a critical flaw in its file upload handling mechanism. The application relies solely on MIME type checking to validate uploaded files, which can be trivially bypassed by attackers.
When a file is uploaded, the server trusts the client-supplied Content-Type header without performing additional validation on the actual file contents. Furthermore, the application preserves the original file extension provided by the user when saving the uploaded file to the server. This combination of weaknesses creates a perfect storm for exploitation.
An attacker can craft a malicious PHP file containing arbitrary code and upload it while specifying a fake MIME type such as image/jpeg or image/png. Since the application does not verify that the file contents actually match the claimed MIME type, and preserves the .php extension, the malicious file is saved to the web-accessible gallery directory where it can be directly executed by browsing to its URL.
Root Cause
The root cause of this vulnerability stems from improper input validation in the file upload functionality. The application commits two critical security mistakes:
Insufficient Content Validation: The application trusts the client-supplied MIME type header rather than inspecting the actual file contents using methods such as magic byte verification or image processing library validation.
Permissive File Extension Handling: The application preserves user-supplied file extensions during the save process, allowing executable file types like .php to be saved to web-accessible directories without restriction.
This combination allows attackers to bypass the intended image-only upload restriction by simply setting the HTTP Content-Type header to an image MIME type while uploading a PHP webshell or other malicious script.
Attack Vector
The attack can be executed remotely over the network without any authentication. An attacker sends a specially crafted HTTP POST request to the gallery/upload.php endpoint. The request contains a malicious PHP file in the multipart form data, but the Content-Type header for the file is set to image/jpeg or another acceptable image MIME type.
The malicious file might contain PHP code that provides a webshell interface, allowing the attacker to execute arbitrary system commands, read sensitive files, modify data, or pivot to other systems on the network. Once uploaded, the attacker simply navigates to the uploaded file's URL (typically in a predictable location within the gallery directory) to trigger code execution.
The attack requires no user interaction and no special privileges, making it highly exploitable in any deployment of the vulnerable application.
Detection Methods for CVE-2025-70457
Indicators of Compromise
- Presence of PHP files with suspicious names or content in the gallery upload directory
- Web server access logs showing requests to newly created PHP files in image directories
- Unusual outbound network connections originating from the web server process
- Evidence of webshell activity such as command execution or file system enumeration
Detection Strategies
- Monitor file system changes in the gallery upload directory for creation of files with executable extensions (.php, .phtml, .php5, etc.)
- Implement web application firewall (WAF) rules to detect MIME type mismatches where the Content-Type header does not match the actual file content
- Analyze web server logs for POST requests to upload.php followed by GET requests to unusual PHP files in the gallery directory
- Deploy file integrity monitoring on web-accessible directories to alert on creation of unexpected script files
Monitoring Recommendations
- Configure real-time alerting for any PHP file creation in designated upload directories
- Implement network traffic analysis to detect potential command and control communications from compromised servers
- Enable comprehensive logging on the web server and review logs regularly for suspicious upload activity
- Monitor for privilege escalation attempts or lateral movement following potential webshell deployment
How to Mitigate CVE-2025-70457
Immediate Actions Required
- Remove or disable the Sourcecodester Modern Image Gallery App if not critical to operations
- Restrict access to the gallery/upload.php endpoint using firewall rules or web server configuration
- Audit the gallery upload directory for any suspicious PHP files and remove any unauthorized scripts
- Implement network segmentation to limit the impact of potential server compromise
Patch Information
No official vendor patch has been identified for this vulnerability at the time of writing. Organizations should consult the GitHub Security Advisory for the latest information on remediation options. The original application can be found at the SourceCodester PHP Project page.
Given the critical nature of this vulnerability and the lack of an official patch, organizations should strongly consider replacing the application with a more secure alternative or implementing comprehensive defensive measures.
Workarounds
- Implement server-side validation that checks actual file content using magic bytes or image processing libraries rather than trusting client-supplied MIME types
- Configure the web server to prevent PHP execution in the upload directory using .htaccess rules or equivalent server configuration
- Rename uploaded files to a server-generated filename with a safe extension (e.g., .jpg) regardless of the original filename
- Deploy a Web Application Firewall (WAF) with rules to block file upload attempts containing PHP code signatures
# Apache .htaccess configuration to prevent PHP execution in upload directory
# Place this file in the gallery/uploads directory
# Disable PHP execution
<FilesMatch "\.ph(p[345]?|t|tml)$">
Order Deny,Allow
Deny from all
</FilesMatch>
# Alternative method using SetHandler
<IfModule mod_php.c>
php_flag engine off
</IfModule>
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
