CVE-2026-87042CVE-2026-87042

The IEEE 1588 (PTP) port implementation in subsys/net/lib/ptp/port.c adopted the logMessageInterval field of a received Delay_Resp message without any validation. port_delay_resp_msg_process() stored the raw wire value (a full-range int8_t) into port_ds.log_min_delay_req_interval, and that value is later used as a shift count by port_timer_set_timeout() when the Delay_Req timer is armed. Values below about -30 truncate the computed timeout to zero, and values with a magnitude of 64 or more perform an undefined shift of a uint64_t; the standards-defined "not applicable" encoding 0x7F fell into the latter case as well. PTP messages are received over unauthenticated link-local traffic (UDP multicast on 224.0.1.129, IPv6 multicast, or raw IEEE 802.3), and the handler accepts a Delay_Resp from any sender as long as the port is a time receiver using the end-to-end delay mechanism and the message echoes the port identity and a pending sequence id — both of which the victim itself broadcasts