CVE-2021-33348 in JFinal
Summary
by MITRE • 06/24/2021
An issue was discovered in JFinal framework v4.9.10 and below. The "set" method of the "Controller" class of jfinal framework is not strictly filtered, which will lead to XSS vulnerabilities in some cases.
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Analysis
by VulDB Data Team • 07/02/2021
The vulnerability identified as CVE-2021-33348 resides within the JFinal web application framework version 4.9.10 and earlier releases, representing a critical cross-site scripting weakness that stems from insufficient input validation within the Controller class implementation. This flaw specifically impacts the "set" method functionality, which serves as a core component for parameter handling and data assignment within the framework's request processing pipeline. The issue manifests when developers utilize the Controller.set() method to assign values to request parameters without proper sanitization, creating opportunities for malicious actors to inject harmful scripts into web applications built on this framework.
The technical nature of this vulnerability aligns with CWE-79, which categorizes cross-site scripting flaws as weaknesses in web applications that allow attackers to inject client-side scripts into web pages viewed by other users. The flaw occurs because the Controller.set() method fails to implement strict filtering mechanisms when processing user-supplied data, particularly when parameters contain special characters or script tags that could be executed in browser contexts. This insufficient validation creates a pathway for attackers to craft malicious payloads that exploit the application's trust in the framework's parameter handling mechanisms, potentially allowing unauthorized script execution within victim browsers.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, data exfiltration, and defacement of web applications. When exploited, the vulnerability allows adversaries to inject malicious JavaScript code that can manipulate the user interface, steal cookies, redirect users to phishing sites, or even execute commands on behalf of the victim. The severity is amplified because JFinal is widely used in enterprise web applications where sensitive data processing occurs, making the potential attack surface particularly valuable to threat actors. The vulnerability affects applications that rely on the Controller.set() method for parameter binding, which is a fundamental operation in most web frameworks, increasing the likelihood of successful exploitation.
Mitigation strategies for CVE-2021-33348 should prioritize immediate framework updates to version 4.9.11 or later, which contain the necessary patches to address the insufficient input filtering. Organizations should implement comprehensive input validation at multiple layers including application-level sanitization, output encoding for all user-supplied content, and the adoption of Content Security Policy headers to limit script execution capabilities. The implementation of proper parameter validation and the use of secure coding practices such as those recommended by the OWASP Top Ten project should be enforced throughout development processes. Additionally, security monitoring systems should be configured to detect anomalous parameter handling patterns, and regular security assessments should be conducted to identify similar vulnerabilities in other framework components or third-party libraries that may present analogous risks. Organizations utilizing the affected framework versions should also consider implementing web application firewalls and runtime application self-protection mechanisms to provide additional defense-in-depth layers against exploitation attempts.