Koel: Incomplete fix for CVE-2026-47260 — systemic SSRF in podcast & radio fetch paths

Koel is a free, open-source music streaming solution. Prior to 9.7.1, outbound podcast and radio fetch paths perform a point-in-time App\Helpers\Network::isPublicHost() or isSafeUrl() check without pinning the validated address, and most paths lack redirect-hop validation and do not revalidate every redirect target. PhanAn\Poddle\Poddle::fromUrl(), PodcastService::getStreamableUrl(), PodcastService::isPodcastObsolete(), App\Rules\HasAudioContentType, and App\Rules\SafeUrl can therefore follow an attacker-controlled redirect to an internal address or connect after DNS rebinding changes a public resolution to a private one. These paths are reachable through podcast and radio APIs, including createPodcastChannel, createInternetRadioStation, refreshPodcasts, apiResource podcasts, and radio/stations, allowing an authenticated user to request internal services or cloud metadata and potentially receive parsed or streamed response content. This issue is fixed in version 9.7.1.