Unauthenticated crash via short URL buffer under-read

Buffer under-read in Zephyr RTOS 3.7 and earlier allows remote attackers to crash its HTTP server via a URL shorter than a registered extension. The http_server_get_content_type_from_extension function subtracts each registered extension length from the URL length without first ensuring that the URL is at least as long, then strncmp reads from the resulting pointer before the URL buffer. An unauthenticated client must reach an application using the affected HTTP server; the out-of-bounds read can terminate the device service.