CVE-2011-4457 in owasp-java-html-sanitizer
Summary
by MITRE
OWASP HTML Sanitizer (aka owasp-java-html-sanitizer) before 88, when JavaScript is disabled, allows user-assisted remote attackers to obtain potentially sensitive information via a crafted FORM element within a NOSCRIPT element.
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Analysis
by VulDB Data Team • 03/17/2019
The vulnerability CVE-2011-4457 affects the OWASP HTML Sanitizer library, specifically impacting versions prior to 88 where JavaScript is disabled. This issue represents a critical security flaw in HTML sanitization that can lead to information disclosure through crafted HTML content. The vulnerability exploits the interaction between HTML parsing behavior and the sanitization process, creating a potential attack vector where malicious actors can bypass security controls to access sensitive data.
The technical flaw manifests when the sanitizer processes HTML content containing a FORM element nested within a NOSCRIPT element while JavaScript is disabled. Under normal circumstances, NOSCRIPT elements are intended to provide fallback content when JavaScript is disabled, but the sanitization library fails to properly handle this specific combination. The vulnerability stems from the library's insufficient parsing logic that does not adequately validate or sanitize nested HTML structures, allowing crafted elements to pass through the sanitization process. This behavior creates a path where attacker-controlled content can be rendered in a way that exposes potentially sensitive information to remote attackers.
The operational impact of this vulnerability extends beyond simple information disclosure, as it represents a bypass of security controls designed to prevent malicious HTML injection. When JavaScript is disabled, users expect enhanced security through reduced attack surface, but this vulnerability undermines those protections by allowing crafted FORM elements to be processed in unexpected ways. Attackers can leverage this flaw to construct malicious HTML payloads that, when processed by vulnerable applications, may reveal sensitive data such as session tokens, user information, or other confidential elements that should remain protected. The vulnerability particularly affects web applications that rely on the OWASP HTML Sanitizer for input validation and security hardening.
Mitigation strategies for CVE-2011-4457 require immediate application of the patched version 88 or later of the OWASP HTML Sanitizer library. Organizations should conduct comprehensive code reviews to identify any applications still using vulnerable versions and ensure proper dependency updates are implemented across all systems. Security teams should also implement additional monitoring for suspicious HTML content patterns and consider implementing web application firewalls to detect and block potentially malicious payloads. The vulnerability aligns with CWE-20: Improper Input Validation and ATT&CK technique T1566.001: Phishing, as it enables attackers to craft malicious HTML content that can be used in social engineering campaigns. Organizations should also consider implementing Content Security Policy headers and other defensive measures to reduce the overall attack surface and prevent exploitation of similar HTML sanitization vulnerabilities.