CVE-2014-9772 in Node.js
Summary
by MITRE
The validator package before 2.0.0 for Node.js allows remote attackers to bypass the cross-site scripting (XSS) filter via hex-encoded characters.
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Analysis
by VulDB Data Team • 05/14/2026
The vulnerability identified as CVE-2014-9772 affects the validator package version 1.6.0 and earlier for Node.js environments, representing a critical security flaw that undermines the intended protection against cross-site scripting attacks. This issue stems from inadequate input validation mechanisms within the package's sanitization routines, specifically failing to properly decode and filter hex-encoded characters that attackers can utilize to circumvent security measures. The vulnerability manifests when the package processes user-supplied input that contains encoded malicious content, allowing attackers to inject potentially harmful scripts that would otherwise be blocked by standard XSS filtering mechanisms.
The technical implementation flaw lies in the validator package's insufficient handling of encoded character sequences during the sanitization process. When hex-encoded characters are present in input data, the package fails to properly decode these sequences before applying XSS filters, resulting in malicious payloads that bypass validation checks. This represents a classic case of improper input validation where the system does not account for multiple encoding layers that attackers might employ to evade detection. The vulnerability aligns with CWE-116, which addresses improper encoding or escaping of output, and specifically demonstrates weaknesses in sanitization routines that fail to handle encoded data properly.
The operational impact of this vulnerability extends beyond simple bypass of XSS protection, as it enables attackers to execute malicious scripts within the context of vulnerable applications. This could lead to session hijacking, data theft, defacement of web applications, or redirection to malicious sites. The remote nature of the attack means that adversaries can exploit this vulnerability without requiring physical access to the target system, making it particularly dangerous in web-facing applications. Attackers can leverage this vulnerability by crafting input containing hex-encoded script tags or other malicious payloads that appear benign to the validator but contain executable code once decoded.
Organizations using affected versions of the validator package should immediately upgrade to version 2.0.0 or later, which includes proper handling of encoded characters during validation processes. Additionally, implementing multiple layers of input validation, including regular expression-based filtering and content security policies, can provide additional protection against similar vulnerabilities. The mitigation strategy should also include regular security assessments of third-party packages and maintaining up-to-date dependency management practices. This vulnerability demonstrates the importance of comprehensive testing for encoding-related issues and aligns with ATT&CK technique T1059.008, which covers the use of scripting languages for execution, as attackers can leverage these bypasses to execute malicious code through web applications.