CVE-2006-5386 in NuralStorm Webmail
Summary
by MITRE
PHP remote file inclusion vulnerability in process.php in NuralStorm Webmail 0.98b and earlier, when register_globals is enabled, allows remote attackers to execute arbitrary PHP code via a URL in the DEFAULT_SKIN parameter.
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Analysis
by VulDB Data Team • 04/24/2026
The vulnerability described in CVE-2006-5386 represents a critical remote file inclusion flaw within the NuralStorm Webmail 0.98b software suite, specifically affecting the process.php script. This issue arises from a fundamental misconfiguration in how the application handles user input parameters, creating an avenue for malicious actors to execute arbitrary code on the target system. The vulnerability is particularly dangerous because it leverages the dangerous practice of enabling register_globals, which was a common but insecure configuration in older php applications. When register_globals is enabled, all HTTP request variables become automatically available as global variables within the PHP script execution context, eliminating the need for explicit variable declaration and opening numerous attack vectors.
The technical exploitation of this vulnerability occurs through manipulation of the DEFAULT_SKIN parameter within the process.php script. Attackers can craft malicious URLs that contain arbitrary PHP code within the skin parameter, which gets included and executed by the vulnerable application when register_globals is active. This creates a classic remote code execution scenario where an attacker can inject and execute arbitrary PHP commands on the web server hosting the NuralStorm Webmail application. The flaw falls under the CWE-88 category of Improper Neutralization of Argument Delimiters in a Command, specifically manifesting as a remote file inclusion vulnerability that allows attackers to specify external resources to be included and executed. The vulnerability directly maps to the ATT&CK technique T1059.007 for Command and Scripting Interpreter: PowerShell, though in this case it operates through PHP inclusion mechanisms rather than PowerShell specifically.
The operational impact of this vulnerability is severe and multifaceted, potentially allowing attackers to gain complete control over the affected web server. Once executed, the remote code injection could enable attackers to upload additional malicious files, establish persistent backdoors, access sensitive user data, or use the compromised server as a launch point for further attacks within the network. The vulnerability affects all versions of NuralStorm Webmail up to and including 0.98b, making it a widespread issue among installations that had not yet updated to secure versions. Organizations running this software with register_globals enabled face immediate risk of compromise, as the vulnerability does not require authentication and can be exploited through simple web browser requests.
Mitigation strategies for this vulnerability must address both the immediate exploitation risk and the underlying configuration issues that make the vulnerability possible. The primary and most effective mitigation is to disable register_globals in the php.ini configuration file, which eliminates the automatic creation of global variables from HTTP request data. Additionally, all affected installations should upgrade to newer versions of NuralStorm Webmail that do not contain this vulnerability. Input validation and sanitization should be implemented to prevent malicious URLs from being processed, though this is secondary to the fundamental configuration fix. Network-level protections such as web application firewalls can help detect and block suspicious requests targeting the vulnerable parameter, while regular security audits should verify that no other similar vulnerabilities exist within the application codebase. The vulnerability serves as a stark reminder of the dangers of legacy PHP configurations and the critical importance of proper input validation in web applications.