CVE-2023-28362 is a vulnerability identified in the Rails web application framework, specifically within the Action Pack component's redirect_to method. This method is commonly used to perform HTTP redirects by setting the Location header in HTTP responses. The vulnerability arises because the redirect_to method allows input values that contain characters not compliant with HTTP header value specifications as defined by relevant RFCs. When such non-compliant characters are included, downstream services or intermediaries that strictly enforce RFC compliance on HTTP headers may reject or remove the Location header from the HTTP response. This removal can disrupt the intended redirect behavior, potentially leading to unintended application logic flows or security controls being bypassed. The vulnerability is classified under CWE-116, which relates to improper encoding or escaping of output, indicating that the root cause is insufficient sanitization or validation of redirect URL inputs. The affected versions are Rails 7.0.5.1 and 6.1.7.4. The CVSS 3.1 base score is 4.0 (medium severity), with an attack vector of local (AV:L), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), no confidentiality impact (C:N), low integrity impact (I:L), and no availability impact (A:N). There are no known exploits in the wild at the time of publication, and no official patches have been linked yet. This vulnerability could cause integrity issues by allowing manipulation of HTTP headers, potentially leading to security bypasses or logic errors in web applications relying on Rails Action Pack for redirects.

For European organizations, the impact of this vulnerability is primarily on web applications built using the affected Rails versions. Since Rails is a popular framework for web development, especially in startups, SMEs, and some enterprise environments, affected applications may experience broken redirect functionality or security bypasses if downstream HTTP intermediaries enforce strict RFC compliance and remove the Location header. This could lead to users being redirected to unintended locations or failure to enforce intended navigation flows, potentially exposing applications to phishing, session fixation, or other logic-based attacks that rely on redirect manipulation. The integrity of application workflows relying on redirects could be compromised, affecting user trust and application reliability. However, the vulnerability does not directly impact confidentiality or availability. The medium severity and local attack vector imply that exploitation requires local access or the ability to influence redirect inputs, limiting the attack surface. European organizations with critical web services using Rails should be aware of this risk, especially those in sectors like finance, e-commerce, and public services where redirect integrity is crucial.

1. Immediate mitigation involves sanitizing and validating all inputs passed to the redirect_to method to ensure they conform to valid HTTP header value characters, effectively preventing injection of illegal characters. 2. Implement strict input validation at the application level to reject or encode characters that are not allowed in HTTP headers before invoking redirect_to. 3. Use allowlists for redirect URLs to restrict redirects only to trusted domains or paths, minimizing the risk of malicious or malformed redirects. 4. Monitor HTTP responses for missing or altered Location headers, especially in environments with strict HTTP intermediaries, to detect potential issues early. 5. Where possible, upgrade to newer Rails versions once official patches addressing this vulnerability are released. 6. Employ web application firewalls (WAFs) configured to detect and block HTTP responses with malformed headers or suspicious redirect patterns. 7. Conduct security testing focusing on redirect behavior and header compliance in staging environments to identify and remediate issues before production deployment.