CVE-2017-0928 in html-janitor
Summary
by MITRE
html-janitor node module suffers from an External Control of Critical State Data vulnerability via user-control of the '_sanitized' variable causing sanitization to be bypassed.
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Analysis
by VulDB Data Team • 03/21/2023
The CVE-2017-0928 vulnerability affects the html-janitor node module, a popular JavaScript library used for sanitizing HTML content in web applications. This security flaw represents a critical weakness in the module's input validation mechanisms, specifically allowing attackers to manipulate internal state variables that control the sanitization process. The vulnerability stems from insufficient validation of user-provided input that ultimately influences how the sanitization routine operates, creating a pathway for malicious actors to bypass intended security controls.
The technical implementation of this vulnerability occurs through the manipulation of the '_sanitized' variable within the html-janitor module's internal processing logic. When user input directly controls this critical state variable, it allows attackers to effectively disable or manipulate the sanitization functions that are designed to remove potentially dangerous HTML elements and attributes. This particular flaw falls under the CWE-191 weakness category, which deals with integer underflow conditions that can lead to unexpected behavior in program execution. The vulnerability operates at the intersection of improper input validation and state management, where user-controllable data directly influences the module's operational parameters.
The operational impact of this vulnerability extends beyond simple bypassing of sanitization measures. Attackers can leverage this weakness to inject malicious HTML content that would normally be filtered out, potentially enabling cross-site scripting attacks, code injection, or other server-side vulnerabilities. When applications rely on html-janitor for HTML sanitization, the bypass allows malicious payloads to persist in the system, creating potential entry points for further exploitation. This vulnerability particularly affects web applications that process user-generated content, as it undermines the fundamental security assumptions of the sanitization process.
Mitigation strategies for CVE-2017-0928 require immediate attention from system administrators and developers. The primary solution involves updating to a patched version of the html-janitor module where the vulnerability has been addressed through proper input validation and state variable handling. Organizations should also implement additional layers of security such as Content Security Policy headers, input sanitization at multiple points in the application stack, and comprehensive testing of user input handling routines. The ATT&CK framework categorizes this vulnerability under T1059.007 for script injection techniques, making it particularly relevant for organizations implementing threat detection and response strategies. Regular security audits and dependency monitoring should be implemented to prevent similar vulnerabilities in other third-party libraries, as this type of flaw represents a common pattern in web application security where insufficient input validation leads to critical state manipulation.