CVE-2015-9531 in Wish Lists Extension
Summary
by MITRE
The Easy Digital Downloads (EDD) Wish Lists 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-2015-9531 vulnerability affects the Easy Digital Downloads Wish Lists extension for WordPress, a popular e-commerce plugin that enables users to create and manage wish lists for digital products. This vulnerability specifically impacts versions of the EDD plugin across multiple release branches including 1.8.x through 1.8.6, 1.9.x through 1.9.9, 2.0.x through 2.0.4, 2.1.x through 2.1.10, 2.2.x through 2.2.8, and 2.3.x through 2.3.6. The flaw stems from improper handling of URL parameters within the add_query_arg function, which is a core WordPress utility for manipulating query strings in URLs. This misconfiguration creates a cross-site scripting vulnerability that allows attackers to inject malicious scripts into web pages viewed by other users.
The technical root cause of this vulnerability lies in the improper sanitization and escaping of user-controllable input parameters within the Wish Lists extension. When the add_query_arg function processes URL parameters, it fails to properly escape or validate input data before incorporating it into the generated URLs. This flaw enables attackers to inject malicious JavaScript code through crafted query parameters that are then executed in the browsers of unsuspecting users. The vulnerability is classified as a classic cross-site scripting flaw, specifically matching CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') and aligns with ATT&CK technique T1203 - Exploitation for Client Execution. The vulnerability manifests when users interact with wish list functionality, particularly when viewing wish lists or when the plugin processes URL parameters from user input.
The operational impact of CVE-2015-9531 is significant for WordPress sites using the affected EDD versions, as it allows for persistent cross-site scripting attacks that can compromise user sessions, steal sensitive information, or redirect users to malicious sites. Attackers can exploit this vulnerability by crafting specially formatted URLs containing malicious JavaScript payloads that are stored in the wish list functionality and subsequently executed when other users view these wish lists. The vulnerability affects both authenticated and unauthenticated users, making it particularly dangerous as it can be exploited through various attack vectors including social engineering, compromised user accounts, or direct URL manipulation. The impact extends beyond simple script execution to potentially enable session hijacking, data theft, or further exploitation of the compromised WordPress installation.
Mitigation strategies for CVE-2015-9531 involve immediate patching of the EDD plugin to versions 1.8.7, 1.9.10, 2.0.5, 2.1.11, 2.2.9, and 2.3.7 respectively, which contain the necessary fixes for the add_query_arg misuse. System administrators should also implement proper input validation and output escaping mechanisms for all user-controllable parameters within the plugin's wish list functionality. Additional defensive measures include implementing content security policies, monitoring for suspicious URL patterns, and conducting regular security audits of installed plugins. Organizations should also consider implementing web application firewalls to detect and block malicious query parameter patterns. The vulnerability highlights the importance of proper parameter sanitization and the need for security-conscious development practices, particularly when working with WordPress core functions like add_query_arg that are frequently used in plugin development. This vulnerability serves as a reminder of the critical importance of input validation and output escaping in preventing cross-site scripting attacks, aligning with security best practices outlined in OWASP Top Ten and NIST cybersecurity guidelines.