CVE-2026-16512CVE-2026-16512

gptp_handle_msg() in subsys/net/l2/ethernet/gptp/gptp.c dereferenced the gPTP header returned by GPTP_HDR() and switched on hdr->message_type without first checking that the received frame carries at least sizeof(struct gptp_hdr) (34) bytes of payload. The header accessor gptp_get_hdr() deliberately never fails for a short buffer — it returns pkt->frags->data and leaves validation to its callers — so a truncated frame produced a header pointer covering memory beyond the received data. The per-message-type checks that follow do not compensate: GPTP_VALID_LEN() reduces to len > 60 once the Ethernet header has been pulled, which is false for every fixed-size gPTP message, so GPTP_CHECK_LEN() never rejects a truncated SYNC, FOLLOWUP, PDELAY_RESP or SIGNALING message. The defect is reached by an unauthenticated peer on the same link sending an Ethernet frame with ethertype 0x88F7 to the PTP multicast address on an interface configured as a gPTP port, with CONFIG_NET_GPTP enabled. Because c