CVE-2004-2294 in PHP-Nuke
Summary
by MITRE
Canonicalize-before-filter error in the send_review function in the Reviews module for PHP-Nuke 6.0 to 7.3 allows remote attackers to inject arbitrary web script or HTML via hex-encoded XSS sequences in the text parameter, which is checked for dangerous sequences before it is canonicalized, leading to a cross-site scripting (XSS) vulnerability.
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Analysis
by VulDB Data Team • 05/13/2025
The vulnerability identified as CVE-2004-2294 represents a critical cross-site scripting flaw within the PHP-Nuke content management system, specifically affecting versions 6.0 through 7.3. This vulnerability resides in the send_review function of the Reviews module, where a fundamental security flaw exists in the order of input validation and canonicalization processes. The issue stems from a classic canonicalize-before-filter error pattern that violates fundamental web application security principles and aligns with CWE-116, which addresses improper encoding or escaping of output.
The technical flaw manifests when user input containing hex-encoded XSS sequences is passed through the text parameter of the send_review function. The system performs validation checks for dangerous sequences before applying canonicalization to the input data, creating a window where malicious code can bypass initial filters. This sequence violation allows attackers to inject arbitrary web scripts or HTML content that would normally be detected and blocked during the filtering phase. The vulnerability specifically exploits the timing of when input sanitization occurs relative to when the data is normalized, creating a path for persistent XSS attacks that can affect all users interacting with the compromised review functionality.
The operational impact of this vulnerability extends beyond simple script injection, as it enables attackers to execute malicious code within the context of users' browsers, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The vulnerability affects the core functionality of PHP-Nuke's review system, which is commonly used in web portals, news sites, and community platforms, making it particularly dangerous for widespread exploitation. This flaw directly maps to attack techniques described in the ATT&CK framework under T1165 - "XSS" and T1531 - "Account Access Removal", as it enables unauthorized access through browser-based attacks.
Mitigation strategies for this vulnerability require immediate patching of affected PHP-Nuke installations to versions that correct the input validation sequence. Organizations should implement proper input canonicalization before filtering, ensuring that all user-supplied data is normalized and validated in the correct order. The recommended approach involves reordering the validation process to canonicalize input data before performing security checks, preventing the bypass of filter mechanisms. Additionally, implementing Content Security Policy headers, using proper HTML escaping techniques, and conducting regular security audits of input handling functions can provide defense-in-depth measures. The vulnerability also highlights the importance of following secure coding practices as outlined in OWASP Top Ten and ISO/IEC 27001 security standards, particularly regarding input validation and output encoding controls that prevent such canonicalization errors from occurring in web applications.