Ella Core: AMF DoS via malformed PathSwitchRequest with empty NR security capability bitstrings

Ella Core is a 5G core designed for private networks. Prior to 1.5.1, Ella Core panics when processing a PathSwitchRequest containing UE Security Capabilities with zero-length NR encryption or integrity protection algorithm bitstrings, resulting in a denial of service. An attacker able to send crafted NGAP messages to Ella Core can crash the process, causing service disruption for all connected subscribers. No authentication is required. This vulnerability is fixed in 1.5.1.