CVE-2013-6430 in Spring Framework
Summary
by MITRE
The JavaScriptUtils.javaScriptEscape method in web/util/JavaScriptUtils.java in Spring MVC in Spring Framework before 3.2.2 does not properly escape certain characters, which allows remote attackers to conduct cross-site scripting (XSS) attacks via a (1) line separator or (2) paragraph separator Unicode character or (3) left or (4) right angle bracket.
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Analysis
by VulDB Data Team • 04/28/2025
The vulnerability described in CVE-2013-6430 represents a critical cross-site scripting flaw within the Spring Framework's Spring MVC component. This issue specifically affects versions prior to 3.2.2 and stems from improper handling of Unicode characters within the JavaScriptUtils.javaScriptEscape method. The flaw manifests when the application processes user input containing certain Unicode characters that should be properly escaped but are not, creating potential entry points for malicious actors to execute XSS attacks. The vulnerability is particularly concerning because it affects the core escaping mechanism used to sanitize output in web applications built on the Spring framework.
The technical implementation of this vulnerability resides in the JavaScriptUtils.javaScriptEscape method located in web/util/JavaScriptUtils.java. This method is responsible for escaping special characters when rendering data within JavaScript contexts to prevent XSS attacks. However, the implementation fails to properly escape four specific Unicode characters including line separators, paragraph separators, and both left and right angle brackets. These characters, when passed through the flawed escaping mechanism, can bypass security measures designed to prevent script injection. The vulnerability is categorized under CWE-79 as a failure to sanitize or incorrectly sanitize user-provided data, which directly enables cross-site scripting attacks.
The operational impact of this vulnerability extends across numerous web applications utilizing Spring MVC components, particularly those that render user-supplied data within JavaScript contexts. Attackers can exploit this weakness by injecting malicious code through carefully crafted Unicode characters that are not properly escaped, potentially allowing them to execute arbitrary JavaScript in the context of victim browsers. This could lead to session hijacking, data theft, defacement of web pages, or redirection to malicious sites. The vulnerability is especially dangerous because it affects the fundamental escaping mechanism that should protect against XSS, meaning that applications using the affected Spring Framework versions may be vulnerable even if they implement other security measures.
The attack surface for this vulnerability encompasses any web application built using Spring MVC that processes user input and outputs it within JavaScript contexts. According to ATT&CK framework categorization, this represents a technique that falls under T1566 - Phishing and T1059 - Command and Scripting Interpreter, specifically targeting the JavaScript execution environment. Organizations using Spring Framework versions before 3.2.2 should immediately implement mitigations including upgrading to patched versions, implementing additional input validation, and deploying web application firewalls. The recommended approach involves applying the official Spring Framework patch, which properly implements Unicode character escaping, along with regular security testing and monitoring to detect potential exploitation attempts. Additionally, organizations should conduct comprehensive code reviews to ensure that all JavaScript output escaping mechanisms are properly implemented and validated.