CVE-2015-5169 in Struts
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Apache Struts before 2.3.20.
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Analysis
by VulDB Data Team • 11/19/2019
The CVE-2015-5169 vulnerability represents a critical cross-site scripting flaw discovered in Apache Struts versions prior to 2.3.20, fundamentally compromising web application security for countless organizations worldwide. This vulnerability resides within the framework's parameter processing mechanisms, specifically in how it handles certain parameters during request parsing, creating an exploitable condition that allows malicious actors to inject arbitrary JavaScript code into web pages viewed by other users. The flaw stems from inadequate input validation and sanitization practices within the Struts framework's core processing pipeline, where user-supplied data is not properly escaped or filtered before being rendered in web responses.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious input parameters that contain JavaScript code, which then gets executed in the context of a victim's browser session. This particular weakness manifests in the framework's handling of certain parameter names and values, particularly those involving nested properties and complex data structures. The vulnerability is categorized under CWE-79 as a failure to sanitize or escape user-supplied data, making it a classic example of cross-site scripting that can be leveraged for session hijacking, credential theft, and various other malicious activities. Attackers can exploit this flaw by injecting malicious scripts through form fields, URL parameters, or HTTP headers, which are then executed in the victim's browser when the application renders the affected page.
The operational impact of CVE-2015-5169 extends far beyond simple data corruption or user inconvenience, as it provides attackers with persistent access to vulnerable applications and their underlying systems. Organizations running affected Struts versions face significant risks including unauthorized data access, privilege escalation, and potential complete system compromise. The vulnerability's exploitation can lead to session fixation attacks where attackers gain unauthorized access to user sessions, or more sophisticated attacks such as credential harvesting through form-based attacks. Security researchers have documented cases where this vulnerability was actively exploited in the wild, targeting financial institutions, government agencies, and enterprise web applications. The impact is particularly severe because Struts was widely adopted across numerous industries, making the potential attack surface exceptionally broad and affecting organizations that may not have been actively monitoring for such specific vulnerabilities.
Mitigation strategies for CVE-2015-5169 require immediate action to upgrade affected systems to Apache Struts 2.3.20 or later versions, as this represents the most effective and comprehensive solution to address the root cause of the vulnerability. Organizations should implement robust input validation and output encoding mechanisms as additional defensive layers, ensuring that all user-supplied data is properly sanitized before processing. The implementation of Content Security Policy headers can provide additional protection against script execution, though this should not be considered a replacement for proper application-level fixes. Security teams should conduct comprehensive vulnerability assessments across all web applications using Struts, particularly focusing on parameter handling and user input processing. Regular security updates and patch management procedures should be strengthened to prevent similar vulnerabilities from being introduced in future versions, aligning with industry best practices outlined in frameworks such as NIST SP 800-53 and ISO 27001 standards. Organizations should also consider implementing web application firewalls and runtime application self-protection mechanisms as additional layers of defense against exploitation attempts.