CVE-2015-9534 in Quota Theme
Summary
by MITRE
The Easy Digital Downloads (EDD) Quota theme for WordPress, as used with EDD 1.8.x before 1.8.7, 1.9.x before 1.9.10, 2.0.x before 2.0.5, 2.1.x before 2.1.11, 2.2.x before 2.2.9, and 2.3.x before 2.3.7, has XSS because add_query_arg is misused.
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Analysis
by VulDB Data Team • 02/08/2025
The vulnerability identified as CVE-2015-9534 affects the Easy Digital Downloads Quota theme for WordPress, specifically targeting versions prior to the listed secure releases. This issue represents a cross-site scripting vulnerability that stems from improper handling of query arguments within the theme's implementation. The flaw manifests when the add_query_arg function is misused, creating opportunities for malicious actors to inject arbitrary JavaScript code into web pages viewed by unsuspecting users. The vulnerability impacts multiple version ranges across the EDD 1.8.x through 2.3.x series, indicating a widespread issue affecting various iterations of the theme.
The technical implementation flaw resides in how the theme processes and sanitizes user input through query parameters. When add_query_arg is improperly utilized, it fails to adequately escape or validate data that flows from user-supplied inputs into the web page context. This misconfiguration allows attackers to inject malicious scripts that execute in the victim's browser when they view affected pages. The vulnerability specifically targets the Quota theme's handling of URL parameters, where user-controllable data is directly incorporated into HTML output without proper sanitization mechanisms. This pattern aligns with CWE-79, which describes cross-site scripting vulnerabilities resulting from insufficient input validation and output encoding.
The operational impact of this vulnerability extends beyond simple script injection, as it enables attackers to perform various malicious activities including session hijacking, credential theft, and redirection to malicious sites. An attacker could craft specially formatted URLs that, when visited by users with administrative privileges, would execute malicious code in their browser context. This capability significantly undermines the security posture of affected WordPress installations, potentially allowing unauthorized access to sensitive administrative functions. The vulnerability's prevalence across multiple EDD versions suggests that organizations running these themes were exposed to risk for extended periods, with the potential for widespread exploitation across various WordPress deployments.
Mitigation strategies for this vulnerability require immediate patching of affected EDD themes to versions 1.8.7, 1.9.10, 2.0.5, 2.1.11, 2.2.9, and 2.3.7 respectively. Organizations should implement comprehensive input validation and output encoding practices, ensuring that all user-supplied data is properly sanitized before being incorporated into web page content. Security measures should include the adoption of Content Security Policy headers to limit script execution and regular security audits of theme implementations. Additionally, administrators should consider implementing web application firewalls and monitoring for suspicious URL patterns that may indicate exploitation attempts. The vulnerability's classification under ATT&CK technique T1566.001 emphasizes the importance of defending against malicious web content delivery and maintaining up-to-date security patches across all WordPress components including themes and plugins.