CVE-2026-12632 Out-of-bounds read in Zephyr PTP message parsing from unvalidated message type

Zephyr's Precision Time Protocol receive handler ptpmsgpostrecv in subsys/net/lib/ptp/msg.c takes the 4-bit message type straight off the wire via ptpmsgtype msg-header.typemajorsdoid & 0xF, range 0-15 and uses it to index the msgsize table. That table only defines entries up to PTPMSGMANAGEMENT...