The NXP LPUART driver in Zephyr contains a flaw that results in a hard fault when an unsupported runtime UART configuration is requested. The bug is triggered because the driver calls LPUART_Deinit at the beginning of configuration, disabling the peripheral clock before validating the requested settings. If the settings are unsupported, the code returns –ENOTSUP without re‑enabling the clock; any subsequent access to the LPUART registers then faults on a gated peripheral, leading to a hard fault that brings the system down. This vulnerability is defined as CWE‑617, an improper validation of input data that incorrectly updates system state.

Affected products are all Zephyr RTOS releases from 2.5.0 onward that include the NXP LPUART driver with CONFIG_UART_USE_RUNTIME_CONFIGURE enabled. The issue persists until the fix commit referenced in the advisory, and therefore applies to all versions that have not yet incorporated that change.

The CVSS score of 5.5 indicates moderate severity, and the EPSS score of less than 1% shows a low estimated likelihood of exploitation at this time. The vulnerability is not listed in CISA's KEV catalog. Exploitation requires an unprivileged user space process that can invoke the uart_configure syscall and provide an unsupported configuration value; the Zephyr verifier simply checks that the memory is readable and forwards the struct unchanged, giving a deterministic way to crash the system. Because the fault is system‑wide, the risk is persistent denial of service across all cores and peripherals.