CVE-2005-2783 in PHP-Fusion
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in PHP-Fusion 6.00.107 and earlier allows remote attackers to inject arbitrary web script or HTML via nested, malformed URL BBCode tags.
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Analysis
by VulDB Data Team • 09/21/2025
The vulnerability identified as CVE-2005-2783 represents a critical cross-site scripting flaw within PHP-Fusion version 6.00.107 and earlier releases. This security weakness resides in the application's handling of BBCode tags, specifically when processing nested and malformed URL BBCode elements. The flaw enables remote attackers to execute malicious scripts in the context of other users' browsers, potentially leading to session hijacking, data theft, or unauthorized actions within the application environment.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within PHP-Fusion's BBCode parser. When the system processes nested URL BBCode tags that contain malformed structures, it fails to properly sanitize the input before rendering it in web pages. This inadequate sanitization allows attackers to inject malicious JavaScript code or HTML content that gets executed when other users view affected pages. The vulnerability specifically targets the BBCode processing engine, which is commonly used for formatting user-generated content in bulletin board systems and content management platforms.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform sophisticated attacks against the application's user base. An attacker could craft malicious BBCode that, when viewed by unsuspecting users, would execute scripts to steal session cookies, redirect users to malicious sites, or even modify content on the vulnerable system. The remote nature of the attack means that exploitation does not require any local access or authentication, making it particularly dangerous for web applications that rely on user-generated content. This vulnerability directly aligns with CWE-79, which describes improper neutralization of input during web page generation, and can be categorized under the ATT&CK technique T1059.007 for scripting languages.
Mitigation strategies for CVE-2005-2783 require immediate action to address the root cause through proper input validation and output encoding. System administrators should upgrade to PHP-Fusion versions that have patched this vulnerability, as the original release contains no built-in protection against such attacks. Additionally, implementing comprehensive input sanitization measures, including proper escaping of special characters in BBCode processing, can prevent the execution of malicious content. Organizations should also consider implementing content security policies and web application firewalls to provide additional layers of protection. The vulnerability demonstrates the critical importance of validating all user inputs and properly encoding output, principles that align with OWASP Top Ten security recommendations and fundamental web application security practices.