CVE-2015-9508 in Commissions Extension
Summary
by MITRE
The Easy Digital Downloads (EDD) Commissions extension 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 CVE-2015-9508 represents a cross-site scripting flaw in the Easy Digital Downloads Commissions extension for WordPress, affecting multiple version ranges of the core EDD plugin. This issue stems from improper handling of URL query parameters through the add_query_arg function, which is a fundamental WordPress utility for constructing URLs with query strings. The vulnerability exists in versions 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, indicating a widespread impact across the EDD Commissions extension's lifecycle. The flaw specifically manifests when the extension processes user-supplied input through query arguments without proper sanitization or escaping mechanisms, creating an avenue for malicious actors to inject arbitrary JavaScript code into the application's response.
The technical root cause of this vulnerability can be traced to CWE-79, which defines Cross-Site Scripting as a weakness where untrusted data is embedded into web pages viewed by other users. In this case, the add_query_arg function, while designed to safely construct URLs with query parameters, was being misused within the EDD Commissions extension in a manner that failed to properly escape or validate the input data before incorporating it into HTML output. When legitimate users interacted with the extension's functionality, particularly in administrative contexts where query parameters might be used for filtering, pagination, or configuration settings, maliciously crafted inputs could be executed in the context of other users' browsers. This misusage creates a persistent XSS vector that allows attackers to execute scripts in the victim's browser session, potentially leading to session hijacking, data theft, or further exploitation of the compromised user's privileges.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to manipulate the administrative interface of WordPress sites running vulnerable versions of EDD Commissions. Since the extension typically operates within the WordPress admin area where users have elevated privileges, successful exploitation could allow attackers to modify commission settings, alter payment records, or even gain full administrative control over the affected site. The vulnerability's presence in multiple version ranges suggests that organizations maintaining WordPress installations with EDD Commissions would need to perform comprehensive vulnerability assessments across their entire plugin ecosystem, as attackers could exploit this weakness to compromise sites regardless of whether they were running the latest stable version. This particular flaw aligns with ATT&CK technique T1548.002, which describes the use of application permissions to escalate privileges, as the XSS could be leveraged to gain administrative access to WordPress installations.
Organizations should implement immediate mitigations including updating to the patched versions of EDD Commissions as specified in the vulnerability timeline, with particular attention to the version boundaries mentioned in the CVE description. The patching process should include thorough testing of the updated extension within a staging environment to ensure compatibility with existing site configurations. Additionally, administrators should implement input validation and output escaping mechanisms at the application level, ensuring that any user-supplied data passed through query parameters is properly sanitized before being incorporated into HTML output. Security measures should include implementing Content Security Policy headers to limit script execution capabilities and monitoring for suspicious query parameter patterns in web server logs. The vulnerability also highlights the importance of following secure coding practices, specifically avoiding the misuse of WordPress core functions like add_query_arg without proper context escaping, which aligns with OWASP Top Ten security recommendations for preventing XSS vulnerabilities in web applications.