CVE-2009-3320 in PaoLink
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in scrivi.php in Zenas PaoLink (aka Pao-Link) 1.0 allows remote attackers to inject arbitrary web script or HTML via the PATH_INFO.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 07/28/2025
The vulnerability described in CVE-2009-3320 represents a classic cross-site scripting flaw within the Zenas PaoLink content management system version 1.0. This particular weakness resides in the scrivi.php script which fails to properly sanitize user input received through the PATH_INFO server variable. The vulnerability classification aligns with CWE-79 which specifically addresses Cross-Site Scripting attacks where untrusted data is incorporated into web page content without proper validation or encoding. The affected application processes URL paths directly without implementing adequate input sanitization mechanisms, creating an exploitable condition that allows malicious actors to inject arbitrary HTML or JavaScript code into web pages viewed by other users.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious URL containing script code within the PATH_INFO parameter that gets processed by the scrivi.php script. Since the application does not validate or escape the input before rendering it in the web response, any script code embedded in the PATH_INFO parameter gets executed in the victim's browser context. This represents a critical security flaw that enables attackers to perform various malicious activities including session hijacking, credential theft, defacement of web content, or redirection to malicious sites. The vulnerability specifically leverages the PATH_INFO server variable which contains the path component of the URL following the script name, making it an attractive target for exploitation since this parameter is often not properly validated in web applications.
The operational impact of this vulnerability extends beyond simple data theft or defacement as it provides attackers with persistent access to user sessions and potentially sensitive information. When users browse to maliciously crafted URLs, their browsers execute the injected scripts which can capture cookies, redirect to phishing sites, or modify page content. The vulnerability affects all users who access the vulnerable application, creating a widespread risk that can be exploited through various vectors including social engineering campaigns, email phishing, or automated scanning tools. From an attack perspective, this flaw maps to the attack technique T1059.007 in the MITRE ATT&CK framework which covers Scripting through the execution of malicious scripts in web browsers.
Mitigation strategies for this vulnerability require immediate implementation of input validation and output encoding mechanisms throughout the application. The primary fix involves sanitizing all user-supplied input from PATH_INFO before processing or displaying it in web responses, with proper HTML entity encoding to prevent script execution. Organizations should implement proper parameter validation that rejects or filters out potentially dangerous characters and patterns commonly used in XSS attacks. Additionally, implementing Content Security Policy headers can provide an additional layer of protection by restricting the sources from which scripts can be loaded and executed. The vulnerability demonstrates the critical importance of proper input validation and output encoding practices as recommended in the OWASP Top Ten security guidelines, specifically addressing the prevention of XSS vulnerabilities through proper data sanitization techniques. Regular security assessments and code reviews should be conducted to identify similar issues in other application components and ensure comprehensive protection against cross-site scripting attacks.