CVE-2009-2893 in Community Classifieds
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in index.php in XZero Community Classifieds 4.97.8 allow remote attackers to inject arbitrary web script or HTML via (1) the postevent parameter in a post action or (2) the _xzcal_y parameter.
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Analysis
by VulDB Data Team • 09/21/2025
The vulnerability identified as CVE-2009-2893 represents a critical cross-site scripting flaw discovered in the XZero Community Classifieds 4.97.8 web application. This issue affects the index.php file and demonstrates a classic input validation weakness that enables malicious actors to execute arbitrary web scripts within the context of authenticated users' browsers. The vulnerability stems from insufficient sanitization of user-supplied input parameters, creating an attack surface where remote adversaries can manipulate application behavior through crafted malicious payloads.
The technical implementation of this vulnerability manifests through two distinct attack vectors that exploit the same underlying flaw in input handling. The first vector targets the postevent parameter during a post action, while the second vector exploits the _xzcal_y parameter. Both parameters fail to properly validate or sanitize incoming data before processing, allowing attackers to inject malicious HTML content or JavaScript code that gets executed when other users view the affected pages. This type of vulnerability falls under CWE-79 which specifically addresses Cross-Site Scripting flaws in web applications, where inadequate input validation permits malicious scripts to be injected into web pages viewed by other users.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, data exfiltration, and redirection to malicious sites. When a victim user accesses a page containing the injected script, the malicious code executes in their browser context, potentially compromising their session cookies, personal information, or even allowing complete account takeover. The vulnerability affects the entire classifieds community platform, potentially impacting thousands of users who may be exposed to the malicious payloads through various classified listings or calendar events.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input validation and output encoding mechanisms throughout the application. The recommended approach involves sanitizing all user-supplied parameters before processing, implementing proper HTML encoding for dynamic content, and deploying Content Security Policy headers to limit script execution. Security measures should include parameter validation using allowlists of acceptable characters, implementing proper escape sequences for HTML content, and regularly updating the application to address known vulnerabilities. Organizations should also consider implementing Web Application Firewalls to detect and block suspicious input patterns, while following ATT&CK framework recommendations for defending against web application attacks. The vulnerability highlights the importance of secure coding practices and demonstrates how seemingly minor input validation gaps can create significant security risks in web applications.