CVE-2006-5511 in JaxUltraBB
Summary
by MITRE
Direct static code injection vulnerability in delete.php in JaxUltraBB (JUBB) 2.0, when register_globals is enabled, allows remote attackers to inject arbitrary web script, HTML, or PHP via the contents parameter, whose value is prepended to the file specified by the forum parameter.
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Analysis
by VulDB Data Team • 04/25/2026
The vulnerability described in CVE-2006-5511 represents a critical direct static code injection flaw within the JaxUltraBB (JUBB) 2.0 bulletin board system. This issue specifically targets the delete.php script and exploits a dangerous configuration where register_globals is enabled, creating a pathway for remote attackers to execute malicious code on affected systems. The vulnerability operates through the contents parameter which, when improperly sanitized, allows attackers to prepend arbitrary code to files specified by the forum parameter, effectively enabling code execution at the system level. This type of vulnerability falls under the CWE-94 category of "Improper Control of Generation of Code" and specifically aligns with CWE-74 which addresses "Improper Neutralization of Special Elements in Output Used by a Downstream Component."
The technical exploitation of this vulnerability requires a specific configuration prerequisite where register_globals is enabled on the web server, which was a common but dangerous practice in older php applications. When an attacker crafts a malicious request to delete.php with a specially formatted contents parameter, the application prepends this content to the file specified by the forum parameter, allowing for arbitrary code injection. This creates a scenario where attackers can execute web scripts, HTML content, or even PHP code directly on the target server, potentially leading to complete system compromise. The attack vector demonstrates the classic pattern of insecure input handling where user-supplied data is directly incorporated into system operations without proper sanitization or validation.
The operational impact of this vulnerability extends beyond simple code injection to encompass full system compromise and potential data breach scenarios. Remote attackers can leverage this vulnerability to execute arbitrary commands, potentially gaining shell access to the server, modifying or deleting critical system files, and establishing persistent backdoors. The vulnerability's exploitation can result in unauthorized access to sensitive user data, forum content, and potentially compromise the entire hosting environment. From an attacker's perspective, this represents a high-value target due to the low complexity of exploitation and high potential for system control, making it a favored target in automated attack campaigns. The vulnerability also demonstrates poor secure coding practices that were prevalent in legacy web applications and highlights the importance of proper input validation and output encoding.
Mitigation strategies for CVE-2006-5511 require immediate attention through multiple defensive measures. The most critical step involves disabling the register_globals directive in php configuration, which eliminates the core prerequisite for exploitation. Additionally, implementing proper input validation and sanitization mechanisms within the delete.php script is essential to prevent malicious content from being processed. The application should validate all user inputs and ensure that any data passed to file operations undergoes strict sanitization. Implementing proper access controls and authentication mechanisms within the bulletin board system will further reduce the attack surface. Organizations should also consider implementing web application firewalls and intrusion detection systems to monitor for exploitation attempts. The vulnerability serves as a prime example of why modern secure coding practices are essential, including input validation, output encoding, and proper error handling as recommended by the OWASP Top Ten and MITRE ATT&CK framework. Regular security audits and code reviews should be conducted to identify similar vulnerabilities in legacy applications, as this type of flaw often indicates broader security issues within the application architecture.