CVE-2009-4858 in Yahoo-Answers-Clone
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in questiondetail.php in Yahoo Answers Clone allows remote attackers to inject arbitrary web script or HTML via the questionid parameter.
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Analysis
by VulDB Data Team • 09/09/2025
The vulnerability identified as CVE-2009-4858 represents a classic cross-site scripting flaw within the Yahoo Answers Clone application's questiondetail.php component. This security weakness enables malicious actors to execute arbitrary web scripts or HTML code in the context of victims' browsers through manipulation of the questionid parameter. The flaw resides in the application's insufficient input validation and output encoding mechanisms, creating an exploitable pathway for persistent XSS attacks. Such vulnerabilities are particularly dangerous in community-driven platforms where user-generated content is prevalent and trust is implicit in the application's functionality.
The technical implementation of this vulnerability stems from the application's failure to properly sanitize or encode user-supplied input before incorporating it into dynamically generated web pages. When the questionid parameter is processed by questiondetail.php, the application directly reflects user input into HTML output without adequate security measures such as input validation, output encoding, or Content Security Policy enforcement. This creates an environment where an attacker can craft malicious payloads that persistently execute within the victim's browser context, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in web applications.
The operational impact of this vulnerability extends beyond simple script injection, as it fundamentally compromises the security integrity of the Yahoo Answers Clone platform. Attackers can leverage this weakness to impersonate legitimate users, steal session cookies, or redirect users to phishing sites that appear legitimate. The persistent nature of XSS vulnerabilities means that once exploited, malicious scripts can remain active for extended periods, continuously affecting users who access affected content. This threat is particularly severe in social networking and question-answering platforms where user trust is paramount and where the platform's reputation depends on maintaining secure user interactions. The vulnerability affects the core functionality of the application by undermining user confidence and potentially enabling large-scale data exfiltration.
Mitigation strategies for CVE-2009-4858 require immediate implementation of comprehensive input validation and output encoding measures. The application should employ strict validation of the questionid parameter to ensure it conforms to expected formats and reject any input containing potentially malicious content. Output encoding should be implemented using context-appropriate encoding mechanisms such as HTML entity encoding when displaying user-supplied data. Additionally, implementing a Content Security Policy would provide an additional layer of protection against XSS attacks by restricting the sources from which scripts can be loaded. Security headers should be configured to prevent script execution from untrusted sources, and regular security testing including automated scanning and manual penetration testing should be conducted to identify similar vulnerabilities. The remediation approach should follow established security frameworks and guidelines such as those provided by the Open Web Application Security Project and align with ATT&CK framework techniques for defending against web-based attacks.