Zephyr 4.5.0 (Working Draft)

We are pleased to announce the release of Zephyr version 4.5.0.

Major enhancements with this release include:

New driver classes

Zephyr 4.5 adds several new driver APIs, including:

• Clock Monitor for runtime observation of clock frequency

An overview of the changes required or recommended when migrating your application from Zephyr v4.4.0 to Zephyr v4.5.0 can be found in the separate migration guide.

The following sections provide detailed lists of changes by component.

Security Vulnerability Related

The following CVEs are addressed by this release:

• CVE 2026-8718 Under embargo until 2026-08-08

• CVE 2026-9263 Under embargo until 2026-06-28

API Changes

Removed APIs and options

• Architectures

  • Xtensa

    • CONFIG_XTENSA_BACKTRACE_EXCEPTION_DUMP_HOOK

• Counter

  • CONFIG_COUNTER_MAXIM_DS3231

• Networking

  • CONFIG_NET_TC_SKIP_FOR_HIGH_PRIO

  • CONFIG_NET_SOCKETS_POLL_MAX

  • net_ipv6_set_hop_limit()

  • net_if_ipv4_get_netmask()

  • net_if_ipv4_set_netmask()

  • net_if_ipv4_set_netmask_by_index()

  • openthread_state_changed_cb_register()

  • openthread_state_changed_cb_unregister()

  • openthread_start()

  • openthread_api_mutex_lock()

  • openthread_api_mutex_try_lock()

  • openthread_api_mutex_unlock()

  • struct openthread_state_changed_cb

  • TLS_CREDENTIAL_SERVER_CERTIFICATE

  • start_11r_roaming

• Random

  • CONFIG_CTR_DRBG_CSPRNG_GENERATOR

  • CONFIG_CS_CTR_DRBG_PERSONALIZATION

• West sign support for imgtool, which was deprecated in Zephyr 4.0, has been removed.

Deprecated APIs and options

• Audio Codec

  • The audio_codec_api struct has been deprecated. Audio codec drivers are now expected to use the DEVICE_API macro to declare their driver API.

• DMIC

  • The _dmic_ops struct has been deprecated. DMIC drivers are now expected to use the DEVICE_API macro to declare their driver API.

• Fuel Gauge

  • Deprecated various fuel gauge property enums and union fields in favor of new versions with explicit unit suffixes.

• LoRa

  • Renamed lora_recv_duty_cycle() to lora_recv_duty_cycle_async() to be consistent with the existing sync/async naming convention.

• Nordic

  • The internal SoC platform Kconfig symbols NRF_PLATFORM_HALTIUM and NRF_PLATFORM_LUMOS have been deprecated. Use specific SOC_SERIES_* Kconfig options instead.

  • The sysbuild Kconfig option SB_CONFIG_NRF_HALTIUM_GENERATE_UICR has been renamed to SB_CONFIG_NRF_GENERATE_UICR.

  • The Nordic SoC headers <haltium_power.h> and <haltium_pm_s2ram.h> have been renamed to <soc_power.h> and <soc_pm_s2ram.h> respectively.

• Ring buffer

  • The ring buffer item API (ring_buf_item_init(), ring_buf_item_put(), ring_buf_item_get(), ring_buf_item_space_get()) has been deprecated in favor of sys_ringq (see sys_ringq Data Structure).

• Networking

  • Deprecated LLMNR support (CONFIG_LLMNR_RESOLVER and CONFIG_LLMNR_RESPONDER). LLMNR is being phased out; use mDNS (CONFIG_MDNS_RESOLVER / CONFIG_MDNS_RESPONDER) instead.

• Networking Link layer

  • Deprecated CONFIG_NET_L2_PTP. Used CONFIG_NET_L2_PTP_TIMESTAMPING instead.

• Work queue

  • k_work_q.thread has been deprecated. Use k_work_q.thread_id instead.

New APIs and options

• Audio

  • pcm_stream_cfg.gain_db

  • audio_codec_eq_cfg

• Bluetooth

  • Audio

    • bt_ascs_register()

    • bt_ascs_unregister()

    • bt_bap_unicast_client_qos_from_group()

    • bt_bap_qos_cfg_eq()

  • Host

    • bt_conn_take()

    • bt_conn_drop()

    • bt_le_per_adv_update_did()

    • bt_le_adv_param.tx_power and BT_LE_ADV_OPT_TX_POWER to request a specific TX power level per extended advertising set.

    • bt_conn_cb.le_param_update_rejected

  • Mesh

    • bt_mesh_lpn_timing

    • bt_mesh_stat_lpn_timing_get()

    • bt_mesh_stat_lpn_timing_reset()

• Crypto

  • CRYPTO_CIPHER_MODE_CFB

  • CRYPTO_CIPHER_MODE_OFB

  • cipher_cfb_op()

  • cipher_ofb_op()

• Devicetree

  • DT_IRQN_BY_NAME

  • DT_INST_IRQN_BY_NAME

• Haptics

  • haptics_monitor

  • haptics_monitor_type

  • haptics_source

  • haptics_config

  • haptics_calibrate()

  • haptics_monitor_get()

  • haptics_monitor_set()

  • haptics_select_source()

  • haptics_set_level()

  • haptics_stream_samples()

• Kernel

  • k_thread_runtime_stats_is_enabled()

  • atomic_test_and_set_bit_to()

• LoRa

  • lora_recv_duty_cycle()

  • lora_recv_duty_cycle_async()

• Network

  • Add net_eth_set_if_type_wifi() to set the ethernet interface type to Wi-Fi.

• Ring buffer

  • sys_ringq (see sys_ringq Data Structure)

New Boards

• Arduino

  • Arduino Nesso N1 (arduino_nesso_n1)

• Seeed

  • Seeed Wio Tracker L1 (wio_tracker_l1)

• WCH

  • WCH CH32V103EVT (ch32v103evt)

New Shields

New Drivers

• GPIO

  • Diodes/Pericom PI4IOE5V6408 8-bit I2C-bus I/O expander (diodes,pi4ioe5v6408).

• Input

  • VIRTIO input device (virtio,input).

• Clock Monitor

  • nxp,cmu-fc — NXP Clock Monitoring Unit (Frequency Check) back-end for the new Clock Monitor subsystem.

  • nxp,cmu-fm — NXP Clock Monitoring Unit (Frequency Meter) back-end for the new Clock Monitor subsystem.

• USB

  • espressif,esp32-usb-otg-fs - Espressif USB-OTG full-speed controller with internal FS/LS PHY.

  • espressif,esp32-usb-otg-hs - Espressif USB-OTG high-speed controller with internal UTMI PHY.

New Samples

• MCTP I2C GPIO Top Node Sample (renamed from mctp_i2c_bus_owner)

• MCTP I3C Top Node Sample (renamed from mctp_i3c_bus_owner)

• samples/drivers/clock_monitor/check_freq — demonstrates WINDOW-mode out-of-window frequency checking on the new Clock Monitor.

• samples/drivers/clock_monitor/measure_freq — demonstrates MEASURE-mode one-shot frequency measurement on the new Clock Monitor.

Libraries / Subsystems

• Crypto

  • Added AES CFB and OFB cipher mode support.

• DFU

  • Added CONFIG_IMG_CUSTOM_SECTOR_SIZE to allow MCUboot to use a different sector size for reducing the swap-using-offset status area size.

• LoRa / LoRaWAN

  • Added a native LoRaWAN backend (CONFIG_LORA_MODULE_BACKEND_NATIVE) that implements LoRaWAN 1.0.x Class A directly on top of the LoRa radio driver, without the Semtech LoRaMac-node dependency. Currently supports the EU868 region.

  • lora_modem_config.sync_word

Devicetree

• DT_NODELABEL_C_TOKEN

• DT_NODELABEL_C_TOKEN_BY_IDX

• TF-M

  • TF-M was updated from version 2.2.2 to version 2.3.0. Release notes can be found at: https://trustedfirmware-m.readthedocs.io/en/tf-mv2.3.0/releases/2.3.0.html

Other notable changes

• Kernel

  • CONFIG_SCHED_CPU_MASK no longer depends on CONFIG_SCHED_SIMPLE. CPU affinity masks are now supported on all three scheduler backends: SCHED_SIMPLE (O(N) list scan), SCHED_SCALABLE (O(N) red/black tree walk), and SCHED_MULTIQ (O(P·N) per-priority bucket scan). See the updated SMP documentation for per-backend performance notes.

  • CONFIG_SCHED_CPU_MASK_PIN_ONLY now enforces the one-CPU-bit invariant at both the API boundary (cpu_mask_mod()) and at queue time (thread_runq()). Calling k_thread_cpu_mask_clear(), k_thread_cpu_mask_enable_all(), or k_thread_cpu_mask_disable() in PIN_ONLY mode triggers an assertion failure. Use k_thread_cpu_pin() to reassign a thread to a different CPU.

• Wi-Fi

  • Removed the samples/net/wifi/test_certs/rsa2k enterprise test certificates (DES-encrypted private keys). Use rsa2k_no_des instead.