CVE-2006-3608 in Flatnuke
Summary
by MITRE
The Gallery module in Simone Vellei Flatnuke 2.5.7 and earlier, when Gallery uploads are enabled, does not restrict the extensions of uploaded files that begin with a GIF header, which allows remote authenticated users to execute arbitrary PHP code via an uploaded .php file.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/25/2025
The vulnerability identified as CVE-2006-3608 affects the Gallery module within Simone Vellei Flatnuke version 2.5.7 and earlier installations. This represents a critical security flaw that stems from inadequate input validation and file extension filtering mechanisms within the file upload functionality. The vulnerability specifically targets the module's handling of image file uploads, where it fails to properly validate the file extensions of uploaded content, creating a path for malicious code execution.
The technical flaw manifests when the Gallery module processes uploaded files that begin with a GIF header but have a .php extension. This occurs because the system performs a superficial check that only examines the initial bytes of the file to determine its type, rather than implementing comprehensive validation of the file's actual content and extension. The GIF header consists of the bytes 47 49 46 38 which are the ASCII values for GIF8, and this header is commonly used in image files. However, the vulnerability exploits the fact that PHP code can be embedded within image files that start with this header, allowing attackers to bypass the intended file type restrictions.
This vulnerability operates under the principle of file upload validation bypass, which is categorized as CWE-434 within the Common Weakness Enumeration framework. The attack vector requires an authenticated user with permissions to upload files through the Gallery module, which aligns with the MITRE ATT&CK technique T1505.003 for "Upload Malicious Content" and T1059.007 for "Command and Scripting Interpreter: JavaScript". The authenticated access requirement reduces the attack surface but does not eliminate the severity of the vulnerability.
The operational impact of this vulnerability is significant as it allows remote authenticated attackers to execute arbitrary PHP code on the affected system. This capability enables attackers to gain full control over the web server, potentially leading to data breaches, system compromise, and further lateral movement within the network. The vulnerability affects the integrity and confidentiality of the web application, as attackers can upload backdoors, web shells, or other malicious payloads that persist beyond the initial attack.
Mitigation strategies for this vulnerability include implementing proper file extension validation that checks both the file header and extension, enforcing strict file type restrictions, and validating uploaded files through multiple methods including content inspection. Organizations should also implement the principle of least privilege for file upload functionality, ensuring that only authorized users with legitimate need can access the Gallery module. Additionally, deploying web application firewalls and implementing proper input validation techniques can provide additional layers of protection against similar vulnerabilities. The fix requires updating to a patched version of Flatnuke or implementing custom validation logic that prevents the execution of PHP code within image files regardless of their initial header bytes.