CVE-2016-6316 in Ruby on Rails
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Action View in Ruby on Rails 3.x before 3.2.22.3, 4.x before 4.2.7.1, and 5.x before 5.0.0.1 might allow remote attackers to inject arbitrary web script or HTML via text declared as "HTML safe" and used as attribute values in tag handlers.
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Analysis
by VulDB Data Team • 09/25/2024
The CVE-2016-6316 vulnerability represents a critical cross-site scripting flaw within Ruby on Rails Action View component that affected multiple version streams including 3.x before 3.2.22.3, 4.x before 4.2.7.1, and 5.x before 5.0.0.1. This vulnerability arises from improper handling of HTML safe content when utilized as attribute values in tag handlers, creating a significant attack surface for remote adversaries seeking to execute malicious scripts within victim browsers. The flaw specifically targets the framework's content security mechanisms that are designed to prevent XSS attacks by marking content as safe for HTML rendering.
The technical root cause of this vulnerability lies in the improper sanitization of content that has been explicitly marked as "HTML safe" within the Rails framework's rendering pipeline. When developers use the html_safe method or similar mechanisms to mark content as safe for HTML output, the framework's tag handlers fail to properly escape or validate attribute values that contain such content. This creates a scenario where malicious input can bypass the normal XSS protection mechanisms that typically prevent script execution within HTML attributes. The vulnerability manifests when user-supplied data that has been marked as safe is subsequently used as attribute values in HTML tag generation, allowing attackers to inject script tags or other malicious content that executes in the context of the victim's browser.
The operational impact of CVE-2016-6316 is substantial as it enables remote attackers to execute arbitrary JavaScript code within the context of any user's browser session who interacts with vulnerable web applications. This can lead to session hijacking, credential theft, data exfiltration, and manipulation of web application functionality. Attackers can craft malicious payloads that exploit the vulnerability by injecting script content into HTML attributes, potentially leading to complete compromise of user sessions and unauthorized access to sensitive application data. The vulnerability affects applications built on affected Rails versions regardless of whether they explicitly use the html_safe method, as the flaw exists within the core rendering logic that processes all content through the tag handling system.
Security mitigations for this vulnerability require immediate patching of affected Rails versions to the patched releases that address the XSS handling in tag attributes. Organizations should implement comprehensive input validation and output encoding strategies that do not rely solely on the html_safe marking mechanism. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and follows ATT&CK technique T1059.007 for script execution through web applications. Additionally, developers should employ Content Security Policy headers, implement proper sanitization of user input, and conduct regular security assessments of their applications to identify similar vulnerabilities in custom code that might leverage the same patterns of HTML safe content handling.