CVE-2009-4819 in PHPhotoalbum
Summary
by MITRE
Multiple unrestricted file upload vulnerabilities in upload.php in PHPhotoalbum allow remote attackers to execute arbitrary code by uploading a file with a (1) .php.pgif or (2) .php.pjpeg double extension, then accessing it via a direct request to the file in albums/userpics/.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/02/2025
The vulnerability identified as CVE-2009-4819 represents a critical security flaw in PHPhotoalbum version 1.3.2 and earlier, where multiple unrestricted file upload capabilities exist in the upload.php script. This vulnerability stems from inadequate input validation and file extension filtering mechanisms that fail to properly sanitize user-supplied filenames. Attackers can exploit this weakness by uploading malicious files with double extensions such as .php.pgif or .php.pjpeg, which bypass standard security checks that typically only examine the final file extension. The flaw allows remote attackers to execute arbitrary code on the target server by simply uploading these specially crafted files and then accessing them through direct requests to the albums/userpics/ directory. This type of vulnerability falls under the CWE-434 category, specifically CWE-434 Unrestricted Upload of File with Dangerous Type, which is classified as a critical weakness in software security practices.
The technical implementation of this vulnerability exploits the server's file handling behavior where the system processes file extensions in a manner that does not properly validate the actual file type or content. When a file with a double extension is uploaded, the system may incorrectly identify the file type based on the final extension, while the server's processing logic may interpret the file differently during execution. The attack vector specifically targets the upload.php script's lack of proper file type validation and the absence of content-based verification mechanisms. The malicious files can contain PHP code that executes when the server processes the uploaded file, potentially allowing attackers to gain full control over the web server, execute arbitrary commands, and establish persistent access to the system. This vulnerability directly relates to the ATT&CK technique T1190 - Exploit Public-Facing Application, which involves leveraging vulnerabilities in publicly accessible web applications to gain unauthorized access.
The operational impact of CVE-2009-4819 is severe and multifaceted, as it allows attackers to achieve complete compromise of the affected web server. Successful exploitation enables remote code execution, which can result in data theft, system infiltration, and potential lateral movement within the network. The vulnerability affects the confidentiality, integrity, and availability of the web application and underlying infrastructure. Organizations running affected versions of PHPhotoalbum face significant risk of unauthorized access, data breaches, and potential use as a foothold for further attacks. The vulnerability's exploitation does not require authentication, making it particularly dangerous as it can be exploited by anyone with access to the web application. The impact extends beyond immediate compromise, potentially leading to long-term persistence and elevated privileges within the compromised environment. The vulnerability also violates fundamental security principles of defense in depth, as proper file upload validation should be implemented at multiple layers of the application architecture to prevent such attacks from succeeding.
Mitigation strategies for CVE-2009-4819 must address both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities. The primary immediate fix involves implementing strict file type validation and content verification mechanisms within the upload.php script, ensuring that all uploaded files are properly validated against a whitelist of allowed extensions and file types. Organizations should implement proper file extension filtering that rejects files with multiple extensions or suspicious file patterns, and should avoid relying solely on file extension checks. The recommended approach includes validating file content using magic number detection rather than just extension-based validation, implementing proper file naming conventions that do not allow arbitrary extensions, and ensuring that uploaded files are stored in directories that are not directly accessible via web requests. Additionally, the application should be updated to a patched version of PHPhotoalbum that addresses this specific vulnerability, and regular security audits should be conducted to identify similar weaknesses in other applications. The mitigation process should also include implementing proper access controls for the upload directory and ensuring that uploaded files are not executable by the web server. Security monitoring and logging should be enhanced to detect suspicious file upload activities and unauthorized access attempts to the affected directories.