CVE-2026-63220: CodeIgniter: Spoofable forwarded HTTPS headers in IncomingRequest::isSecure()

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.