CVE-2015-9535 in Shoppette Theme
Summary
by MITRE
The Easy Digital Downloads (EDD) Shoppette 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-2015-9535 affects the Easy Digital Downloads Shoppette theme for WordPress, specifically targeting versions of the EDD plugin prior to certain patch releases. This issue represents a cross-site scripting vulnerability that arises from improper handling of URL query parameters within the theme's implementation. The vulnerability is particularly concerning as it impacts multiple version streams of the EDD plugin, spanning from 1.8.x through 2.3.x, indicating a widespread exposure across the plugin's ecosystem. The misconfiguration occurs in how the add_query_arg function is utilized, which creates opportunities for malicious actors to inject harmful scripts into web pages viewed by other users.
The technical flaw stems from the insecure usage of WordPress's add_query_arg function, which is designed to safely manipulate URL query parameters. When this function is improperly implemented within the Shoppette theme, it fails to adequately sanitize or escape user-supplied input before incorporating it into HTML output contexts. This misapplication creates a pathway for attackers to inject malicious JavaScript code through URL parameters, which then executes in the browsers of unsuspecting users who visit affected pages. The vulnerability manifests when the theme processes query arguments without proper validation, allowing arbitrary code execution within the context of a user's browser session. This behavior aligns with CWE-79, which describes cross-site scripting flaws where untrusted data is improperly incorporated into web pages without adequate sanitization or escaping mechanisms.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform a range of malicious activities including session hijacking, credential theft, and redirection to malicious websites. Users who visit compromised pages may unknowingly have their browser sessions compromised, potentially leading to unauthorized access to their WordPress accounts or other connected services. The vulnerability affects not just the theme's functionality but also the broader security posture of WordPress installations, as it leverages the plugin's legitimate URL handling mechanisms to execute unauthorized code. Attackers can craft malicious URLs that, when clicked by victims, trigger the XSS payload, making this vulnerability particularly dangerous in phishing campaigns or when exploited through social engineering tactics.
Mitigation strategies for CVE-2015-9535 require immediate patching of affected EDD plugin versions to the recommended secure releases, specifically upgrading 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 monitoring of their WordPress installations to identify any remaining vulnerable themes or plugins and ensure all components are updated to current secure versions. Additionally, administrators should consider implementing Content Security Policy headers to add an extra layer of protection against XSS attacks, though this should not be considered a substitute for proper patching. The vulnerability demonstrates the importance of proper input validation and output escaping practices, particularly when dealing with URL parameters and user-supplied data in web applications. Security teams should also review their incident response procedures to ensure rapid deployment of patches and monitoring for exploitation attempts, as this vulnerability fits within the ATT&CK framework's web application attack patterns under the category of code injection techniques.