CVE-2015-9522 in QR Code Extension
Summary
by MITRE
The Easy Digital Downloads (EDD) QR Code 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 CVE-2015-9522 vulnerability affects the Easy Digital Downloads QR Code extension for WordPress, a popular e-commerce plugin that enables merchants to generate QR codes for digital product purchases. This security flaw exists in multiple versions of the EDD plugin including 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 vulnerability stems from improper handling of user-supplied input through the add_query_arg function, which is a WordPress utility function designed to manipulate query parameters in URLs. When this function is misused in the context of the QR Code extension, it fails to properly sanitize or escape output, creating an avenue for cross-site scripting attacks that can be exploited by malicious actors.
The technical implementation flaw occurs when the extension processes user input or dynamic content to generate QR codes, specifically when the add_query_arg function is called without adequate sanitization of the parameters being added to the query string. This misconfiguration allows attackers to inject malicious scripts into URLs that are subsequently rendered in web browsers, particularly when QR code generation pages are accessed. The vulnerability manifests as a reflected cross-site scripting condition where malicious payloads can be executed in the context of a victim's browser session, potentially leading to unauthorized actions or data theft. The issue is classified as a CWE-79: Improper Neutralization of Input During Web Page Generation, which represents one of the most common and dangerous web application vulnerabilities in the industry. The ATT&CK framework categorizes this under T1059.001: Command and Scripting Interpreter - PowerShell, though more specifically it aligns with T1566.001: Credential Access - Phishing, as the attack vector involves injecting malicious content that can harvest user credentials or perform unauthorized transactions.
The operational impact of this vulnerability is significant for WordPress sites using the affected EDD plugin versions, as it exposes merchants and customers to potential session hijacking, credential theft, and unauthorized financial transactions. Attackers can craft malicious URLs containing XSS payloads that, when scanned by users with QR code readers, execute scripts in their browsers to steal session cookies, redirect them to malicious sites, or perform unauthorized actions on their behalf. The vulnerability particularly affects e-commerce environments where users may be prompted to scan QR codes for payment processing, making it a prime target for financial fraud. The risk is amplified because the affected versions span multiple major release lines, indicating a widespread exposure across numerous WordPress installations. Organizations using the Easy Digital Downloads plugin without proper patching are vulnerable to attacks that can compromise user accounts, steal sensitive information, and potentially disrupt business operations through unauthorized transactions. The remediation requires immediate updating of the EDD plugin to versions that properly sanitize query arguments before incorporating them into generated QR codes, along with implementing proper input validation and output escaping measures throughout the plugin's codebase.
The exploitation of this vulnerability demonstrates the critical importance of proper input validation and output escaping in web applications, particularly those handling financial transactions and user data. Security practitioners should note that this issue represents a common pattern where well-intentioned WordPress functions like add_query_arg are misused without proper sanitization, creating security gaps that can be easily exploited by attackers. The vulnerability highlights the need for comprehensive security testing of third-party plugins, especially those handling user input or generating dynamic content, as well as the importance of maintaining up-to-date software versions to protect against known exploits. Organizations should implement regular security audits of their WordPress installations, monitor for vulnerable plugin versions, and establish robust patch management processes to ensure timely remediation of security issues like CVE-2015-9522. Additionally, network monitoring and web application firewalls can provide additional layers of protection against exploitation attempts, though the most effective defense remains maintaining current software versions and following secure coding practices that prevent the injection of malicious content into web applications.