CVE-2019-16772 in serialize-to-js
Summary
by MITRE
The serialize-to-js NPM package before version 3.0.1 is vulnerable to Cross-site Scripting (XSS). It does not properly mitigate against unsafe characters in serialized regular expressions. This vulnerability is not affected on Node.js environment since Node.js's implementation of RegExp.prototype.toString() backslash-escapes all forward slashes in regular expressions. If serialized data of regular expression objects are used in an environment other than Node.js, it is affected by this vulnerability.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 03/08/2024
The serialize-to-js npm package version 3.0.1 and earlier contains a cross-site scripting vulnerability that arises from inadequate handling of unsafe characters in serialized regular expression objects. This vulnerability specifically impacts applications that deserialize regular expression data and subsequently render it in web contexts where XSS attacks can occur. The flaw stems from the package's failure to properly escape forward slashes and other special characters when converting regular expression objects to JavaScript strings, creating potential injection vectors for malicious code execution.
The technical root cause of this vulnerability aligns with CWE-79, which describes cross-site scripting flaws occurring when untrusted data is directly embedded into web pages without proper sanitization or escaping. When regular expression objects are serialized using the vulnerable package, the resulting JavaScript code contains unescaped forward slashes that can break out of script contexts when rendered in browsers. This issue is particularly concerning because regular expressions often contain forward slashes as part of their syntax, and the serialize-to-js package fails to properly escape these characters during the serialization process. The vulnerability demonstrates how seemingly benign data serialization operations can introduce security risks when proper input validation and output escaping mechanisms are not implemented.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to execute arbitrary JavaScript code in the context of affected applications. This allows for session hijacking, data theft, defacement of web applications, and potential lateral movement within compromised environments. The vulnerability is particularly dangerous in applications that process user-provided data through regular expressions and subsequently display this data in web interfaces without proper sanitization. Attackers can craft malicious regular expression objects that, when serialized and executed, can bypass security controls and establish persistent access to affected systems. This vulnerability affects web applications that rely on the serialize-to-js package for processing regular expressions, making it a significant concern for developers working with JavaScript serialization frameworks.
Organizations should immediately update to serialize-to-js version 3.0.1 or later to remediate this vulnerability, as this version includes proper escaping mechanisms for forward slashes and other special characters in regular expression serialization. Security teams should also implement additional safeguards such as content security policies to mitigate potential impact from any remaining vulnerable code. The mitigation strategy should include comprehensive code reviews to identify all instances where regular expressions are serialized and subsequently rendered in web contexts. This vulnerability serves as a reminder of the importance of proper input sanitization and output escaping in web applications, and aligns with ATT&CK technique T1211 which describes the use of malicious code injection in web applications. Organizations should also consider implementing automated dependency scanning tools to identify vulnerable packages and ensure timely patching of similar security issues across their software supply chain.