CodeIgniter: Spoofable forwarded HTTPS headers in IncomingRequest::isSecure()

Impact

IncomingRequest::isSecure() trusted the X-Forwarded-Proto and Front-End-Https headers from any incoming request. In affected deployments, an attacker could spoof these headers and cause the application to incorrectly treat an HTTP request as secure.

This may impact applications that rely on isSecure(), force_https(), forceGlobalSecureRequests, or similar logic to enforce HTTPS-only access or make security-sensitive decisions.

Exploitability depends on deployment configuration. Applications are most exposed if the backend is reachable directly over HTTP, or if a reverse proxy/load balancer forwards client-supplied forwarding headers without stripping or overwriting them.

Patches

Upgrade to v4.7.4 or later.

Workarounds

Users who cannot upgrade immediately should enforce HTTP-to-HTTPS redirects outside CodeIgniter, for example with Apache .htaccess/virtual host rules, nginx server blocks, Caddy site config, or load balancer redirect rules.

Users should also ensure that reverse proxies strip or overwrite client-supplied X-Forwarded-Proto and Front-End-Https headers before forwarding requests to the application.