CVE-2015-9520 in Per Product Emails Extension
Summary
by MITRE
The Easy Digital Downloads (EDD) Per Product Emails 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-2015-9520 vulnerability affects the Easy Digital Downloads Per Product Emails extension for WordPress, representing a cross-site scripting flaw that emerged in multiple versions of the EDD plugin ecosystem. This vulnerability specifically targets the extension's handling of URL parameters through the add_query_arg function, creating a pathway for malicious actors to inject harmful scripts into web pages viewed by unsuspecting users. The affected versions span across several major release branches 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, indicating a widespread issue within the plugin's codebase that persisted across multiple versions. The vulnerability stems from improper sanitization of user-supplied input within the extension's query argument handling mechanism, which directly violates established security principles for web application development. According to CWE classification, this represents a CWE-79: Cross-site Scripting vulnerability where the flaw occurs in the data processing layer of the web application, specifically in how the add_query_arg function processes and outputs URL parameters without adequate validation or encoding.
The technical exploitation of this vulnerability occurs when malicious users craft specially formatted URLs containing script tags or other malicious payloads within query parameters that are processed by the add_query_arg function. When legitimate users visit these crafted URLs, the malicious scripts execute in their browser context, potentially leading to session hijacking, data theft, or further compromise of the affected WordPress installation. The misused add_query_arg function fails to properly encode or sanitize the output, allowing attackers to inject JavaScript code that executes within the browser of any user who encounters the maliciously constructed URL. This flaw creates a persistent threat vector since the malicious code can be embedded in various parts of the extension's functionality, including email templates, product pages, or administrative interfaces where query parameters are processed. The vulnerability's impact extends beyond simple script execution as it can be leveraged for more sophisticated attacks including credential theft, redirection to malicious sites, or manipulation of the user's browsing experience through DOM manipulation.
The operational impact of CVE-2015-9520 is significant for WordPress sites utilizing the Easy Digital Downloads plugin, particularly those running affected versions of the Per Product Emails extension. Organizations relying on these e-commerce platforms face potential exposure to unauthorized access, data breaches, and compromised user sessions. The vulnerability affects not only the end users who may encounter malicious scripts but also the site administrators who may be targeted through attacks that exploit the extension's functionality. Attackers can leverage this flaw to gain unauthorized access to customer data, manipulate product information, or redirect users to phishing sites. The widespread nature of the affected versions means that many WordPress installations across different industries and organizations could be vulnerable, creating a substantial attack surface for threat actors. The vulnerability aligns with ATT&CK technique T1566.001 which involves spearphishing with a malicious attachment or link, as attackers could exploit this XSS vulnerability to deliver malicious payloads through carefully crafted email links or web content that users would naturally click.
Mitigation strategies for CVE-2015-9520 involve immediate patching of the affected Easy Digital Downloads plugin to versions that properly address the XSS vulnerability in the add_query_arg implementation. Site administrators should ensure all instances of the Per Product Emails extension are updated to the latest stable versions that contain proper input sanitization and output encoding mechanisms. Additionally, implementing proper input validation and output encoding practices throughout the application codebase can prevent similar vulnerabilities from occurring in other parts of the WordPress ecosystem. Security monitoring should include scanning for malicious URLs or scripts that may attempt to exploit this vulnerability, while also implementing proper access controls and user session management to limit the potential damage from successful exploitation. Organizations should also consider implementing Content Security Policy headers to provide an additional layer of protection against XSS attacks, although this mitigation is secondary to the primary fix of updating the vulnerable plugin versions. The vulnerability demonstrates the critical importance of proper input validation and output encoding in web applications, particularly when handling user-supplied data through URL parameters, and serves as a reminder of the need for continuous security auditing of third-party plugins and themes.