This is a bugfix release for Zephyr 4.2.1. This will be the final release of Zephyr 4.2, as it has now reached EOL status: https://docs.zephyrproject.org/4.2.0/releases/index.html#supported-releases
The following issues are addressed by this release:
#55186 posix: fnmatch: fix known bugs
#61464 USB device stack (new and old) assertion on STM32
#84934 USB devices broken on STM32F723XX MCUs after clock enable changes
#92397 Missing fallback to a base board.dts when using a board variant without specific dts file
#93668 esp32s3: pr 91027 results in periph_rtc_dig_clk8m_get_freq() returning zero
#93943 Unable to build LVGL samples on Ubuntu 22.04 for native_sim
#93986 Unable to build LVGL with picolibc from source/module
#96841 FRDM_K64F: arch.arm.user.stack.float test fail
#97269 Improve UVC compliance and support MacOS
#97304 arch: arm: start threads on privileged stack
#97593 Flash writing is broken for some dual-bank STM32H7 variants
#98077 wifi: credentials: Unable to connect with multiple SSIDs saved
#98231 Build System: defconfig: Base defconfig not used on fully qualified oot board
#98469 drivers: bluetooth: h4: insufficient buffer for header + payload
#98668 drivers: entropy: non-stop RNG ISR firing on STM32WB09
#98768 STM32F303 bxCAN: Last 2 bytes corrupted on TX pin, but registers are correct
#98936 net: ICMPv4 packets can be reported to ICMPv6 handlers (and vice versa)
#99369 Zephyr 4.2 release notes indicate wrong TF-M version
#99412 drivers/ethernet/eth_native_tap uses a deprecated kconfig option in 4.2
#99682 net: lib: dns: Unpacking query name can overflow the destination buffer
#99797 MCUmgr: OS: DateTime: Millisecond parsing erroneous
#99895 npcx9m6f_evb and frdm_k64f: kernel.common.stack_protection_arm_fpu_sharing fails
#100212 No event code filterint for LVGL pointer process
#100296 west packages pip --install fails with permission error
#100754 bt test commands not working/crashing for nRF54LM20A DK board
#101236 NXP: Failed to disable random-mac-address in ethernet driver.
#102307 CI runner out of disk on backports to 4.2
#102338 macos-13 runner used in v4.2-branch
#102393 Bluetooth: Mesh: Missing provisioning PDU length check can result in out of bound write
#102395 Bluetooth: Mesh: Invalid SegN in provisioning PDU may result in out-of-bound write
#102635 gpio: mcux: Potential infinite interrupt hang when configuring
#103029 NVS startup fails after power loss during final ATE write
#99535 Issue with STM32 Ethernet and KSZ8081 Phy
#104208 IPv4/6 fragmentation memory leak
#104248 DNS query packet length check
#104253 driver: clock_control: RCC_BDCR_LSEDRV_Pos undefined using STM32L0
#104652 net: socketcan: length not always verified
#104748 [mcumgr] error codes of group "stat" incorrect
#104948 net: lib: socket: tls: Potential out-of-bounds write in socket_op_vtable::connect
#105374 drivers: gpio: sam: callback called when interrupt disabled