AzuraCast is a self-hosted web radio management suite. In AzuraCast before 0.23.8, the station webhook URL validation in AbstractConnector::

AzuraCast is a self-hosted web radio management suite. In AzuraCast before 0.23.8, the station webhook URL validation in AbstractConnector::getValidUrl() (backend/src/Webhook/Connector/AbstractConnector.php), used by the Generic and Discord webhook connectors, rejects only URLs whose host is a literal link-local IP address (169.254.0.0/16 or fe80::/10). Loopback addresses and RFC1918 private ranges are not rejected, and any non-literal-IP hostname causes the IP parsing call to throw, which skips the check entirely. A user holding only the station-scoped WebHooks permission can therefore configure a webhook pointing at an internal, loopback, or private-network target and cause the server to issue an outbound HTTP POST containing the station's Now Playing data, resulting in server-side request forgery. The PUT /station/{id}/webhook/{id}/test endpoint allows the same low-privileged user to trigger the request on demand. At the time of the advisory no patched version was available.