CVE-2015-9529 in Stripe Extension
Summary
by MITRE
The Easy Digital Downloads (EDD) Stripe 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 vulnerability identified as CVE-2015-9529 affects the Easy Digital Downloads Stripe extension for WordPress, a popular e-commerce plugin that enables merchants to accept payments through Stripe. This security flaw exists in multiple versions of the EDD plugin, specifically impacting 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. The issue stems from improper handling of user input within the add_query_arg function, which is a WordPress utility function designed to manipulate URL query parameters. This misconfiguration creates a cross-site scripting vulnerability that can be exploited by malicious actors to inject malicious scripts into the application's response.
The technical flaw manifests when the add_query_arg function is used inappropriately within the Stripe extension's codebase, failing to properly sanitize or escape user-supplied input before incorporating it into HTML output. This improper usage allows attackers to inject malicious JavaScript code through query parameters that are then executed in the context of other users' browsers. The vulnerability is particularly concerning because it affects the payment processing functionality of the e-commerce platform, potentially enabling attackers to steal sensitive payment information, session cookies, or perform unauthorized transactions on behalf of users. The flaw falls under CWE-79, which represents Cross-Site Scripting, and aligns with ATT&CK technique T1566.001 for initial access through malicious web content.
The operational impact of this vulnerability extends beyond simple script injection, as it can compromise the entire payment processing ecosystem of affected WordPress sites. Attackers could exploit this weakness to redirect users to fraudulent payment pages, steal credit card information, or manipulate transaction data. The vulnerability affects websites that handle sensitive financial information, making it particularly dangerous for businesses relying on the Easy Digital Downloads platform for their online sales. Given that the affected versions span multiple minor releases, the potential attack surface is substantial, encompassing numerous websites that may have been running outdated versions of the plugin for extended periods. The issue demonstrates the critical importance of proper input validation and output escaping in web applications, particularly those handling financial transactions where security breaches can result in significant financial losses and reputational damage.
Organizations affected by this vulnerability should immediately upgrade to the patched versions of the Easy Digital Downloads plugin, specifically versions 1.8.7, 1.9.10, 2.0.5, 2.1.11, 2.2.9, and 2.3.7 respectively. Additionally, administrators should implement proper input sanitization practices and conduct thorough security audits of their WordPress installations, particularly reviewing all third-party plugins for similar vulnerabilities. The mitigation strategy should include monitoring for suspicious activity in payment processing and ensuring that all user-supplied data is properly escaped before being rendered in HTML contexts. Security teams should also consider implementing web application firewalls and content security policies to provide additional defense-in-depth measures against similar XSS vulnerabilities in the future.