CVE-2023-28362 in actionpack Gem
Summary
by MITRE • 01/09/2025
The redirect_to method in Rails allows provided values to contain characters which are not legal in an HTTP header value. This results in the potential for downstream services which enforce RFC compliance on HTTP response headers to remove the assigned Location header.
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Analysis
by VulDB Data Team • 04/25/2025
The vulnerability identified as CVE-2023-28362 resides within the redirect_to method implementation in the Ruby on Rails web application framework. This flaw represents a critical security issue that undermines the integrity of HTTP redirect mechanisms and can lead to bypass of intended access controls. The vulnerability stems from insufficient validation of input parameters passed to the redirect_to method, allowing malicious actors to inject characters that violate HTTP header standards. When Rails processes these malformed redirect values, it generates HTTP response headers containing illegal characters that downstream HTTP servers or proxies may reject or strip entirely. This behavior creates a significant attack surface where legitimate redirect functionality can be subverted or completely neutralized. The issue directly relates to CWE-113, which describes improper neutralization of special elements used in HTTP headers, and aligns with ATT&CK technique T1566.001 for phishing through social engineering. The vulnerability affects applications that rely on Rails' built-in redirect functionality, potentially enabling attackers to manipulate access control flows and bypass authentication mechanisms.
The technical exploitation of this vulnerability occurs when an attacker provides malicious input to the redirect_to method that contains characters forbidden in HTTP header values according to RFC standards. These illegal characters typically include control characters, line breaks, or other special sequences that would normally be rejected by compliant HTTP servers. When Rails processes such inputs, it creates Location headers containing these invalid characters, which subsequent HTTP processing layers may interpret as malformed content and strip from the response entirely. This results in redirects failing silently without the user being properly directed to the intended destination. The flaw essentially allows attackers to craft inputs that bypass normal redirect validation, potentially enabling them to manipulate user navigation or circumvent security controls. The vulnerability is particularly dangerous because it operates at the HTTP protocol level, affecting the fundamental communication mechanism between web applications and clients. This type of vulnerability falls under the category of header injection attacks, where attackers manipulate HTTP headers to achieve unintended behavior in the application stack.
The operational impact of CVE-2023-28362 extends beyond simple redirect failures to encompass broader security implications for applications relying on Rails' authentication and authorization mechanisms. When redirects are stripped or ignored due to malformed headers, attackers can exploit this behavior to bypass intended access controls, potentially leading to unauthorized access to protected resources. Applications may experience inconsistent behavior where legitimate redirects work while malicious ones are silently discarded, creating confusion for both developers and security monitoring systems. The vulnerability can be particularly problematic in applications implementing multi-factor authentication, session management, or role-based access controls, where proper redirect handling is crucial for maintaining security boundaries. Additionally, this issue can be leveraged in combination with other vulnerabilities to create more sophisticated attack vectors, such as bypassing security headers or manipulating user sessions through carefully crafted redirect chains. Organizations using affected Rails versions may find their security monitoring systems flagging legitimate traffic as suspicious due to the inconsistent redirect behavior, leading to operational overhead and potential false positive scenarios.
Organizations should immediately upgrade to Rails versions that contain patches for this vulnerability, typically those released after the vulnerability disclosure date. The recommended mitigation involves applying the official security patches provided by the Rails team, which include enhanced input validation for redirect parameters. Additionally, organizations should implement comprehensive input sanitization at multiple layers of their application architecture, including validating all redirect URLs against a whitelist of approved domains and paths. Network-level protections such as Web Application Firewalls can provide additional defense-in-depth by monitoring for suspicious redirect patterns and blocking malformed HTTP headers. Security teams should also conduct thorough vulnerability assessments to identify all applications using affected Rails versions and ensure proper patch management procedures are in place. Monitoring should be enhanced to detect anomalous redirect behavior or patterns that might indicate exploitation attempts. The fix addresses the root cause by implementing stricter validation of Location header values, ensuring that only RFC-compliant characters are allowed in redirect destinations, thereby preventing downstream HTTP servers from rejecting or stripping the headers. This vulnerability demonstrates the critical importance of proper input validation in web applications and highlights the need for robust HTTP header handling mechanisms in modern web frameworks.