CVE-2015-9525 in Recurring Payments Extension
Summary
by MITRE
The Easy Digital Downloads (EDD) Recurring Payments 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 • 02/07/2025
The CVE-2015-9525 vulnerability affects the Easy Digital Downloads recurring payments extension for WordPress, representing a cross-site scripting flaw that emerged due to improper implementation of the add_query_arg function. This vulnerability specifically impacts versions of 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, creating a persistent security risk for WordPress sites utilizing this e-commerce extension. The flaw stems from the extension's failure to properly sanitize or escape user-supplied input when constructing URLs through the add_query_arg function, which is a core WordPress utility for manipulating query parameters in URLs.
The technical exploitation of this vulnerability occurs when malicious actors inject malicious scripts through parameters that are processed by add_query_arg without adequate sanitization. When the vulnerable extension handles recurring payment requests or administrative operations, it fails to properly escape output that originates from user inputs or external sources, allowing attackers to inject malicious JavaScript code into URLs that are subsequently rendered in web browsers. This misimplementation creates a pathway for attackers to execute arbitrary code within the context of a victim's browser session, potentially compromising user data and system integrity. The vulnerability directly aligns with CWE-79, which describes cross-site scripting flaws resulting from improper handling of untrusted data in web applications, and demonstrates how improper input validation can lead to severe security consequences.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform unauthorized actions on behalf of users with administrative privileges. When exploited, the XSS flaw allows threat actors to steal session cookies, modify user settings, or redirect victims to malicious websites that can harvest sensitive information. The vulnerability particularly affects e-commerce environments where users may have elevated privileges, creating opportunities for attackers to compromise entire WordPress installations or access customer payment information. The widespread adoption of Easy Digital Downloads makes this vulnerability particularly dangerous, as it affects numerous websites handling sensitive financial transactions and personal data. Attackers can leverage this weakness to establish persistent access to compromised systems, potentially leading to data breaches, financial fraud, or complete system compromise.
Mitigation strategies for CVE-2015-9525 primarily involve immediate patching of affected EDD versions to the latest available releases that address the XSS vulnerability in the recurring payments extension. System administrators should implement proper input validation and output escaping measures for all user-supplied data, particularly when constructing URLs or handling query parameters. The WordPress security community recommends implementing Content Security Policy headers to limit script execution and prevent unauthorized code injection, while also ensuring that all plugins and themes undergo regular security audits. Organizations should also deploy web application firewalls and monitor for suspicious URL patterns that may indicate exploitation attempts, as well as maintain comprehensive backup strategies to quickly restore systems in case of successful compromise. This vulnerability serves as a critical reminder of the importance of proper input sanitization and output escaping in web applications, particularly in e-commerce systems where user data protection is paramount.