CVE-2015-7580 in Ruby on Rails
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in lib/rails/html/scrubbers.rb in the rails-html-sanitizer gem before 1.0.3 for Ruby on Rails 4.2.x and 5.x allows remote attackers to inject arbitrary web script or HTML via a crafted CDATA node.
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Analysis
by VulDB Data Team • 07/06/2022
The CVE-2015-7580 vulnerability represents a critical cross-site scripting flaw within the rails-html-sanitizer gem, specifically affecting Ruby on Rails 4.2.x and 5.x versions prior to 1.0.3. This vulnerability resides in the lib/rails/html/scrubbers.rb file, which serves as a crucial component for sanitizing HTML content in Rails applications. The flaw stems from inadequate handling of crafted CDATA nodes during the HTML sanitization process, creating a pathway for malicious actors to bypass security controls designed to prevent XSS attacks. The vulnerability operates at the intersection of input validation and output sanitization, where the sanitizer fails to properly escape or remove potentially dangerous CDATA sections that could contain malicious scripts.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious CDATA node containing embedded JavaScript or HTML code within the rails application's HTML sanitization pipeline. When the rails-html-sanitizer processes such input, the CDATA node is not properly escaped or stripped, allowing the malicious content to persist in the sanitized output. This behavior violates the fundamental security principle that sanitized content should be free from executable code and dangerous markup patterns. The vulnerability is particularly insidious because it exploits a weakness in the sanitization logic rather than bypassing authentication or authorization mechanisms, making it difficult to detect through traditional security controls. The flaw is categorized under CWE-79 as Cross-Site Scripting, specifically manifesting as a failure to sanitize input properly, and aligns with ATT&CK technique T1203 for Exploitation for Client Execution through web-based attacks.
The operational impact of CVE-2015-7580 extends beyond simple script injection, potentially enabling attackers to execute arbitrary code in victims' browsers, steal session cookies, perform unauthorized actions on behalf of users, or redirect users to malicious websites. Applications using affected versions of the rails-html-sanitizer gem are at risk of becoming vectors for more sophisticated attacks including session hijacking, data exfiltration, and credential theft. The vulnerability affects web applications that rely on Rails' HTML sanitization features for processing user-generated content, making it particularly dangerous in applications with rich text editors, comment systems, or any functionality that accepts and displays untrusted HTML input. Organizations deploying Rails applications without updating to the patched version remain vulnerable to persistent XSS attacks that could compromise user sessions and application integrity.
Mitigation strategies for CVE-2015-7580 require immediate application of the security patch to rails-html-sanitizer gem version 1.0.3 or later, which properly handles CDATA node sanitization. System administrators should also implement additional defensive measures including Content Security Policy (CSP) headers, input validation at multiple layers, and regular security auditing of HTML sanitization processes. Organizations should conduct thorough vulnerability assessments to identify applications using affected gem versions and ensure proper patch management procedures are in place. The fix addresses the core sanitization logic by properly escaping or removing CDATA sections during the HTML processing pipeline, preventing malicious code from persisting in sanitized output. Security monitoring should include detection of unusual HTML content patterns and regular testing of input sanitization functionality to prevent similar vulnerabilities from emerging in the future.