CVE-2015-9506 in Amazon S3 Extension
Summary
by MITRE
The Easy Digital Downloads (EDD) Amazon S3 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-2015-9506 vulnerability affects the Easy Digital Downloads Amazon S3 extension for WordPress, a popular plugin used for digital downloads and e-commerce functionality. This security flaw specifically targets versions of the EDD plugin across multiple 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. The vulnerability stems from improper handling of user input within the add_query_arg function, which is a core WordPress function designed to manipulate URL query parameters. When the Amazon S3 extension processes user-supplied data, it fails to properly sanitize or escape the input before incorporating it into URLs, creating a path for malicious actors to inject cross-site scripting payloads.
The technical implementation of this vulnerability involves the misuse of WordPress's add_query_arg function which is intended to safely add query parameters to URLs. However, in the affected EDD versions, the extension does not properly validate or escape the input parameters before they are processed through this function. When a user accesses a page that utilizes the S3 extension functionality, maliciously crafted URLs containing script tags or other XSS payloads can be injected into the query string. These payloads are then executed in the context of other users' browsers who visit the same page, as the malicious code is included in the URL construction without proper sanitization. This creates a persistent cross-site scripting vulnerability that allows attackers to execute arbitrary JavaScript code in the victim's browser.
The operational impact of this vulnerability is significant for WordPress sites using the affected EDD plugin versions, particularly those handling digital downloads and e-commerce transactions. Attackers can exploit this vulnerability to steal user sessions, perform unauthorized actions on behalf of victims, redirect users to malicious websites, or inject malware into the victim's browsing environment. The vulnerability affects not only the site administrators but also regular users who may inadvertently trigger the XSS payload through malicious links or compromised pages. Given that EDD is a widely used plugin for digital commerce, the potential attack surface is extensive, with compromised sites potentially serving as entry points for further attacks or as command and control centers for botnet activities.
Mitigation strategies for CVE-2015-9506 focus on immediate patching and input validation measures. Organizations should immediately upgrade to the patched versions of the EDD plugin, specifically versions 1.8.7, 1.9.10, 2.0.5, 2.1.11, 2.2.9, and 2.3.7 respectively, which address the improper use of add_query_arg. Additionally, administrators should implement proper input validation and output escaping mechanisms throughout their WordPress installations, particularly in any custom code or plugin modifications that handle URL parameters. The vulnerability aligns with CWE-79, Cross-site Scripting, and follows patterns commonly associated with ATT&CK technique T1566.001, which involves creating malicious links or content to execute code in the target environment. Network-based mitigations such as web application firewalls and content security policies can provide additional protection, though the most effective defense remains the timely application of security patches. Regular security audits and monitoring of plugin versions should be implemented to prevent similar vulnerabilities from persisting in the WordPress ecosystem.