CVE-2002-2255 in phpBB
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in search.php in phpBB 2.0.3 and possibly earlier versions allows remote attackers to inject arbitrary web script or HTML via the search_username parameter in searchuser mode.
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Analysis
by VulDB Data Team • 08/29/2025
The vulnerability identified as CVE-2002-2255 represents a classic cross-site scripting flaw within the phpBB bulletin board system version 2.0.3 and potentially earlier releases. This security weakness specifically targets the search.php script and occurs when the application processes the search_username parameter in searchuser mode. The flaw enables malicious actors to inject arbitrary web scripts or HTML code into the application's response, creating a persistent security risk for all users interacting with the vulnerable system. This type of vulnerability falls under the category of CWE-79 - Improper Neutralization of Input During Web Page Generation, which is a fundamental weakness in web application security that has been consistently documented in industry security frameworks.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious payload containing script code and submits it through the search_username parameter. When the phpBB application processes this input without proper sanitization or encoding, the malicious code becomes embedded within the HTML response generated by the search.php script. This allows the injected script to execute within the context of other users' browsers who view the search results page. The vulnerability is particularly dangerous because it operates at the application layer where user input is directly reflected back to the browser without adequate input validation or output encoding mechanisms. This attack vector aligns with ATT&CK technique T1566.001 - Phishing: Spearphishing Attachment, as it can be delivered through seemingly legitimate search functionality.
The operational impact of CVE-2002-2255 extends beyond simple script injection, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, redirection to malicious sites, and data exfiltration from users' browsers. Since phpBB is a widely deployed forum software, the potential attack surface is extensive, affecting numerous websites and organizations that rely on this platform for community discussions and user interactions. The vulnerability's persistence in the application's codebase for several years following its discovery indicates a fundamental flaw in the input handling process that was not adequately addressed in the software's development lifecycle. Organizations running affected versions face significant risk of compromised user sessions and potential data breaches, as users may unknowingly execute malicious code when browsing forum content.
Mitigation strategies for this vulnerability involve implementing proper input validation and output encoding mechanisms within the phpBB application. The most effective approach is to sanitize all user input before processing and to encode output data appropriately when rendering it within HTML contexts. Administrators should immediately upgrade to patched versions of phpBB 2.0.4 or later, as these releases contain the necessary security fixes. Additional protective measures include implementing content security policies, using web application firewalls to filter malicious requests, and conducting regular security audits of web applications. The vulnerability demonstrates the critical importance of input validation and output encoding practices, which are fundamental requirements in secure software development and align with security standards such as OWASP Top Ten and NIST cybersecurity frameworks that emphasize the need for proper data sanitization and context-aware output handling in web applications.