CVE-2015-9519 in PDF Stamper Extension
Summary
by MITRE
The Easy Digital Downloads (EDD) PDF Stamper 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-2015-9519 vulnerability affects the Easy Digital Downloads PDF Stamper extension for WordPress, representing a cross-site scripting flaw that emerged in specific version ranges of the EDD plugin ecosystem. This vulnerability stems from improper handling of URL parameters within the add_query_arg function, which is a core WordPress utility for managing query string parameters in URLs. The flaw exists across multiple minor version branches including 1.8.x, 1.9.x, 2.0.x, 2.1.x, 2.2.x, and 2.3.x, indicating a widespread issue within the extension's implementation that required multiple patch releases to address.
The technical exploitation of this vulnerability occurs when the PDF Stamper extension processes user-supplied input through URL parameters without proper sanitization or escaping mechanisms. The add_query_arg function, while designed to safely construct URLs with query parameters, was misapplied in this context, allowing malicious actors to inject arbitrary JavaScript code into URLs that are subsequently rendered in web browsers. This misapplication creates a pathway for attackers to execute malicious scripts in the context of a victim's browser session, potentially compromising user data and browser integrity.
The operational impact of this vulnerability extends beyond simple script execution, as it represents a critical security weakness that could enable attackers to perform various malicious activities including session hijacking, data theft, and redirection to malicious websites. The vulnerability affects legitimate WordPress installations that utilize the EDD plugin ecosystem, making it particularly dangerous as it targets widely used e-commerce functionality. The fact that multiple version ranges are affected indicates that the flaw was persistent and likely not addressed through immediate patching cycles, creating extended exposure windows for potential exploitation.
Organizations and WordPress administrators should prioritize immediate patching of affected versions to mitigate this vulnerability, as the XSS flaw provides attackers with a straightforward method to compromise user sessions and execute malicious code. The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in software applications, and demonstrates how improper input validation and output encoding can create security risks even within well-established plugin ecosystems. Security practitioners should implement additional monitoring and input validation measures to detect potential exploitation attempts, while the ATT&CK framework categorizes this as a technique involving client-side code execution that could lead to further compromise of user systems and data.