CVE-2013-7454 in Node.js
Summary
by MITRE
The validator module before 1.1.0 for Node.js allows remote attackers to bypass the cross-site scripting (XSS) filter via nested forbidden strings.
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Analysis
by VulDB Data Team • 05/14/2026
The vulnerability identified as CVE-2013-7454 affects the validator module for Node.js versions prior to 1.1.0, representing a critical security flaw in input validation mechanisms. This issue specifically targets the cross-site scripting filter implementation, which is designed to prevent malicious scripts from being injected into web applications through user input. The vulnerability arises from inadequate string sanitization and pattern matching within the validation logic, allowing attackers to craft malicious inputs that can bypass the intended security controls.
The technical flaw stems from the validator module's inability to properly handle nested or encoded forbidden strings that would typically trigger the XSS filter. Attackers can exploit this weakness by constructing input sequences where forbidden characters or patterns are embedded within other valid content or encoded in ways that circumvent the validation checks. This allows malicious payloads to pass through the security filter undetected, potentially enabling attackers to inject harmful scripts that can execute in the context of other users' browsers. The vulnerability operates at the application layer and specifically targets the validation logic that should prevent XSS attacks, making it particularly dangerous for web applications that rely on this module for input sanitization.
The operational impact of this vulnerability is significant for Node.js applications that depend on the validator module for security purposes. Applications using affected versions may experience unauthorized code execution in users' browsers, leading to potential data theft, session hijacking, or malicious redirection. The bypass mechanism allows attackers to circumvent security controls that should protect against common XSS attack vectors, potentially compromising user data and application integrity. This vulnerability particularly affects web applications that process user input through the validator module and rely on its XSS protection features, making it a serious concern for any system handling untrusted input from web users.
Mitigation strategies for this vulnerability include immediately upgrading to validator module version 1.1.0 or later, which contains the necessary fixes for the nested string bypass issue. Organizations should also implement additional defensive measures such as input encoding, content security policies, and regular security testing of validation logic. The fix addresses the core issue by improving the pattern matching algorithms and ensuring that nested or encoded forbidden strings are properly detected and rejected. Security teams should conduct comprehensive testing to verify that all input validation points are properly protected and consider implementing multiple layers of security controls to reduce reliance on any single validation mechanism. This vulnerability aligns with CWE-79 - Cross-site Scripting and relates to ATT&CK technique T1203 - Exploitation for Client Execution, highlighting the importance of proper input validation in preventing client-side exploitation.