CVE-2026-75084CVE-2026-75084

The CC1200 sub-GHz IEEE 802.15.4 driver takes the PHY packet length from the first byte of the radio's RX FIFO in get_packet_length() and validates it in verify_rxfifo_validity() (drivers/ieee802154/ieee802154_cc1200.c). That validation only enforced a lower bound (pkt_len < 3); its second clause rejects a FIFO that holds more bytes than declared and therefore never bounds large values. Because the driver configures the radio for variable packet length with PKT_LEN = 0xFF, the length byte is an over-the-air value of 0-255 that reached net_pkt_rx_alloc_with_buffer() and the subsequent SPI burst read unclamped. An unauthenticated attacker within radio range can transmit a frame that presents a length byte above the IEEE 802.15.4 maximum of 127 while the chip's 128-byte RX FIFO has not overflowed, so the driver's RX_FIFO_ERROR pre-check does not fire. Reaching this state depends on RF framing and timing, since the RX thread is driven off the PKT_SYNC_RXTX signal and may sample the FIFO b