CVE-2010-2479 in Htmlpurifier
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in HTML Purifier before 4.1.1, as used in Mahara and other products, when the browser is Internet Explorer, allows remote attackers to inject arbitrary web script or HTML via unspecified vectors.
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Analysis
by VulDB Data Team • 09/20/2021
The vulnerability identified as CVE-2010-2479 represents a cross-site scripting flaw within HTML Purifier library versions prior to 4.1.1, specifically impacting web applications that utilize this sanitization tool. This weakness manifests when the target browser environment is Microsoft Internet Explorer, creating a significant security risk for applications that rely on HTML Purifier for content sanitization. The vulnerability affects not only Mahara but also numerous other products that incorporate this library, highlighting the widespread nature of the issue. The flaw resides in how HTML Purifier handles certain input vectors when processing content for Internet Explorer browsers, creating opportunities for malicious actors to bypass security measures that should prevent injection of harmful scripts.
The technical implementation of this vulnerability stems from insufficient sanitization of user-provided content when HTML Purifier processes input for Internet Explorer compatibility. The unspecified vectors mentioned in the description suggest that attackers can exploit various input points within the application to inject malicious scripts that will execute in the context of a victim's browser session. This particular weakness is classified under CWE-79, which specifically addresses cross-site scripting vulnerabilities, and aligns with ATT&CK technique T1203, which covers exploitation of web application vulnerabilities. The vulnerability exploits the way HTML Purifier handles HTML entities and script tags when generating output for Internet Explorer, allowing attackers to craft payloads that bypass the intended security filtering mechanisms. The flaw becomes particularly dangerous because it leverages the specific parsing behavior of Internet Explorer to execute malicious code in the context of legitimate user sessions.
The operational impact of CVE-2010-2479 extends beyond simple script injection, as it enables attackers to perform session hijacking, steal sensitive information, manipulate user interfaces, and potentially gain unauthorized access to protected resources. When exploited, this vulnerability can allow attackers to execute arbitrary JavaScript code in the context of authenticated user sessions, potentially leading to complete compromise of user accounts and sensitive data exposure. The implications are particularly severe in educational platforms like Mahara, where users may have access to confidential academic information, personal data, and institutional resources. The vulnerability's exploitation requires no special privileges beyond basic web access, making it particularly dangerous as it can be leveraged by anyone who can submit content to affected applications. This creates a significant risk for organizations that depend on HTML Purifier for content management and user-generated content processing.
Mitigation strategies for CVE-2010-2479 primarily focus on upgrading to HTML Purifier version 4.1.1 or later, which contains the necessary patches to address the Internet Explorer-specific sanitization issues. Organizations should conduct comprehensive vulnerability assessments to identify all applications using affected versions of HTML Purifier and implement immediate upgrades. Additionally, implementing proper input validation and output encoding at multiple layers of the application architecture can provide defense-in-depth protection. Security teams should also consider implementing content security policies and monitoring for suspicious script injection attempts. The vulnerability demonstrates the importance of browser-specific testing in security libraries and highlights the need for comprehensive testing across different browser environments. Organizations should also establish procedures for rapid patch deployment and maintain updated inventories of all third-party libraries to quickly identify and remediate similar vulnerabilities. The incident underscores the critical nature of keeping security libraries current and the potential consequences of relying on outdated components in web applications.