CVE-2014-4571 in VN-Calendar
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in vncal.js.php in the VN-Calendar plugin 1.0 and earlier for WordPress allow remote attackers to inject arbitrary web script or HTML via the (1) fs or (2) w parameter.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 03/11/2019
The CVE-2014-4571 vulnerability represents a critical cross-site scripting flaw discovered in the VN-Calendar WordPress plugin version 1.0 and earlier. This vulnerability exists within the vncal.js.php script which serves as a JavaScript component for calendar functionality. The flaw stems from insufficient input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before incorporating it into dynamically generated web content. Attackers can exploit this vulnerability by manipulating specific parameters in the URL to inject malicious scripts that execute in the context of other users' browsers.
The technical implementation of this vulnerability involves two primary attack vectors through the fs and w parameters within the vncal.js.php file. These parameters appear to control calendar display settings and time window configurations respectively. When user input is directly reflected in the JavaScript output without proper sanitization, it creates an environment where malicious payloads can be executed. The vulnerability manifests as a classic reflected XSS attack where the malicious script is embedded in the URL and executed when the victim accesses the compromised page. This type of vulnerability falls under CWE-79 which specifically addresses Cross-Site Scripting flaws in web applications.
The operational impact of CVE-2014-4571 extends beyond simple script injection, as it can enable attackers to perform session hijacking, steal sensitive cookies, redirect users to malicious sites, or even execute arbitrary commands on vulnerable systems. Given that WordPress plugins often have elevated privileges and access to user data, successful exploitation could compromise entire WordPress installations. The vulnerability is particularly dangerous because it affects the core calendar functionality that many users interact with regularly, making it an attractive target for mass exploitation campaigns. Security researchers categorize this under the ATT&CK framework as part of the Initial Access phase, specifically leveraging Web Application Attacks to establish footholds within target environments.
Mitigation strategies for CVE-2014-4571 require immediate plugin updates to version 1.1 or later where the vulnerability has been patched. System administrators should implement proper input validation and output encoding mechanisms that sanitize all user-supplied data before it is processed or displayed. The patch typically involves implementing proper HTML escaping for all dynamic content generation and validating parameter inputs against expected formats. Organizations should also consider implementing Content Security Policy headers to limit script execution and prevent unauthorized code injection. Regular security audits of WordPress plugins and themes remain crucial for identifying similar vulnerabilities, as this issue demonstrates the ongoing need for proper input validation in web applications. The vulnerability highlights the importance of keeping all web application components updated and following secure coding practices that prevent injection attacks through proper parameter handling and output encoding.