CVE-2017-16016 in Sanitize-html
Summary
by MITRE
Sanitize-html is a library for scrubbing html input of malicious values. Versions 1.11.1 and below are vulnerable to cross site scripting (XSS) in certain scenarios: If allowed at least one nonTextTags, the result is a potential XSS vulnerability.
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Analysis
by VulDB Data Team • 03/21/2023
The sanitize-html library represents a critical security vulnerability that affects applications relying on HTML sanitization for input validation and security. This vulnerability specifically targets versions 1.11.1 and earlier, where the library fails to properly handle certain HTML tag configurations that could lead to cross site scripting attacks. The flaw occurs within the library's sanitization logic when specific nonTextTags are permitted in the configuration, creating a pathway for malicious code execution. The vulnerability demonstrates a fundamental weakness in how the library processes HTML input sanitization, particularly when dealing with tag allowances that should otherwise be restricted.
The technical implementation of this vulnerability stems from improper handling of the nonTextTags parameter within the sanitize-html library. When developers configure the library to allow certain non-text HTML tags, the sanitization process fails to adequately validate or escape content within these tags, potentially allowing attackers to inject malicious scripts. This issue directly relates to CWE-79 which describes cross site scripting vulnerabilities arising from improper input handling and output encoding. The vulnerability's exploitation requires a specific configuration scenario where the library is set to permit certain nonTextTags, making it context-dependent but still highly dangerous when present.
The operational impact of CVE-2017-16016 extends beyond simple script injection, as it can enable attackers to execute arbitrary JavaScript code within the context of affected applications. This could lead to session hijacking, data theft, defacement of web applications, or further exploitation through techniques such as credential harvesting or privilege escalation. The vulnerability affects web applications that process user-generated content through the sanitize-html library, particularly those that do not properly validate their configuration parameters. Attackers can leverage this weakness by crafting malicious HTML input that, when processed through the vulnerable library, executes unintended code in users' browsers, creating a persistent security risk across all affected systems.
Organizations should immediately upgrade to sanitize-html version 1.11.2 or later, which contains the necessary patches to address this vulnerability. Security teams must review all applications utilizing this library to ensure proper configuration parameters are set and that nonTextTags are carefully restricted. The recommended mitigation includes implementing strict input validation, monitoring for suspicious HTML content, and conducting regular security assessments of third-party libraries. Additionally, organizations should consider implementing web application firewalls and content security policies as additional defensive measures. This vulnerability aligns with ATT&CK technique T1203 which describes exploitation of vulnerabilities in web applications through cross site scripting attacks, emphasizing the need for comprehensive security controls that address both the immediate patching requirements and broader application security posture.