The UpdateHub OTA client's start_coap_client() function in Zephyr leaks CoAP/DTLS socket descriptors on connection setup failures due to improper cleanup logic. Specifically, when socket creation fails and subsequent DTLS socket options or connection calls fail, the cleanup gate does not trigger, leaving the socket descriptor open and overwritten on the next attempt. This leak accumulates with each failed connection attempt, which occurs periodically via the OTA client's autohandler poll or on-demand API calls. The leak leads to exhaustion of the socket pool, causing device-wide networking degradation until reboot. The vulnerability is low severity because the leak rate is limited by the default 24-hour poll interval, the effect is gradual, and only devices with the UpdateHub client enabled are affected. There are no memory corruption, information disclosure, or authentication impacts.

The vulnerability causes a denial-of-service condition by leaking socket descriptors on each failed connection attempt to the UpdateHub server. Over time, this exhausts the socket pool, degrading networking functionality device-wide until the device is rebooted. The leak rate is bounded by the OTA poll interval, so the impact is gradual rather than immediate. There are no impacts on confidentiality, integrity, or authentication.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, be aware that the leak occurs only if the UpdateHub client is enabled and connection attempts fail. Rebooting the device restores networking functionality by clearing leaked sockets. No other mitigation actions are specified.