The Zephyr Project announced Zephyr RTOS 4.5.0 on October 28, 2026. The GitHub release was published at 22:23 UTC that day, alongside a release blog post by Benjamin Cabé and a walkthrough video. It is a final release, not a release candidate, as confirmed by the GitHub release, the project blog and the live documentation page.

This is a big release. It adds two new CPU architectures, an experimental multimedia framework, a lot of new networking protocols, six new driver classes and a change to how SBOMs are generated, which matters for compliance. The release notes also list 178 new boards and 29 new shields.

Two new architectures: TriCore and Hexagon

The headline addition is support for two architectures that are new to Zephyr: Infineon TriCore, the core family used in Infineon's AURIX automotive microcontrollers, and the Qualcomm Hexagon DSP. According to the project blog, both come with QEMU targets: qemu_tc3x and qemu_tc4x for TriCore, and qemu_hexagon for Hexagon. The documentation lists these as emulation of the AURIX TC39x, the AURIX TC4Dx and Hexagon respectively.

The blog also says what is missing. The TriCore QEMU and the Hexagon toolchain do not yet ship in the Zephyr SDK. Developers who want to try either port will have to source those pieces themselves for now. The architectures are in the tree, but they are not yet as easy to set up as Arm or RISC-V.

Networking: faster stack, many more protocols

The GitHub release notes describe up to 21% higher TCP throughput in the zperf loopback benchmark. The blog gives more context: it also reports up to 12% higher UDP throughput, with UDP gains of 7 to 12% on x86 and Cortex-M3 and 1 to 3.5% on RISC-V. The benchmark runs in QEMU's instruction-counting mode, which makes results deterministic and comparable from one release to the next. These are emulated loopback figures, not measurements of radio or Ethernet throughput on real silicon, so expect real-world results to differ.

The protocol list is longer than in most Zephyr releases. Per the GitHub release, 4.5 adds:

  • QUIC and HTTP/3
  • RTP (RFC 3550)
  • An SSH server and client, including an SSH shell backend
  • An MCP server (Model Context Protocol, to let AI agents use tools exposed by a device)
  • IPv4 forwarding and NAT
  • An IPv6 router role and DHCPv6 prefix delegation

The MCP server is the item most likely to get attention. The blog describes a demo in which devicetree bindings declare class: sensor and the MCP server registers one tool per enabled sensor, so adding a sensor to the board adds a tool. An AI agent connected to the device can then use those tools to query its sensors. Taken together with the SSH shell backend and IPv4 forwarding/NAT, Zephyr devices can now act as small network appliances and remotely managed nodes, not just endpoints.

mpipe: an experimental multimedia pipeline

Zephyr 4.5 introduces mpipe, an experimental multimedia pipeline framework inspired by GStreamer: source, transform and sink elements linked into a zero-copy pipeline. The blog notes that the video and display elements are still under review in pull requests #108344 and #108345, and that its demo used them cherry-picked. The framework has landed, but the elements most people would want for camera-to-screen pipelines are not merged yet. Treat it as something to test, not to build a product on.

New driver classes

The GitHub release lists six new driver APIs: Buzzer, Clock Monitor, DALI, LIN, MUX and Pulse IO. Two of them stand out. DALI is the Digital Addressable Lighting Interface. LIN is the Local Interconnect Network automotive serial bus, which fits alongside the TriCore/AURIX port. With a standard API, applications can target these buses the same way across vendors, instead of using vendor-specific HAL calls.

SBOMs: SPDX 3.0 arrives, but stays opt-in

The blog title links this release to the EU Cyber Resilience Act (CRA). Zephyr 4.5 can now emit SPDX 3.0 software bills of materials, including a Build profile that records how the image was built. According to the blog and the release notes, SPDX 2.3 remains the default and SPDX 3.0 is selected explicitly. The blog's example is:

west build -b <board> <app> -- -DCONFIG_BUILD_OUTPUT_META=y
west spdx -d build --spdx-version 3.0

Because 2.3 stays the default, teams can move to the newer format when they are ready.

Security, simulation and tooling

The release notes list several smaller changes that affect day-to-day development:

  • Hardware-accelerated PSA Crypto on selected Silicon Labs, NXP and STM32 devices. The notes do not list every part, so check the specific SoC before relying on it.
  • New native_sim peripherals: Wi-Fi, audio, video, LEDs and host directory mounts, which means more application code can run and be tested on a Linux host.
  • VirtIO drivers for QEMU covering block, input, GPIO, I2C and SPI.
  • Twister, Zephyr's test runner, gains multi-device testing and multi-toolchain builds.
  • Heap sanitizers: CONFIG_SYS_HEAP_SANITIZER_ASAN (for native_sim) and CONFIG_SYS_HEAP_KASAN (real targets).
  • Tracing improvements: a terminal viewer, Perfetto export, a shell, and an ITM backend.

The heap sanitizers and Perfetto export are useful additions. Heap corruption is a common cause of hard-to-reproduce RTOS bugs, and the blog notes that Perfetto export lets you open a Zephyr trace in the same UI you may already use for Linux.

Boards, shields and contributors

The documentation release notes count 178 new boards and 29 new shields. The contributor numbers do not match across sources. The project blog says over 1,200 individuals contributed, which it calls a record. The description of the official "What's New in Zephyr 4.5?" video says nearly 1,300. Both come from the project, and neither source explains the difference.

What It Means for Makers

Who it is for: Most hobbyists on Arm Cortex-M, ESP32 or RISC-V boards will get the most out of the networking work, the new driver classes, the extra native_sim peripherals and the new board support. Two groups get more specific benefits. The TriCore port and LIN API are aimed at automotive and AURIX developers. The Hexagon port is aimed at people working with Qualcomm DSPs.

What it enables: QUIC/HTTP/3 and SSH on-device bring Zephyr closer to the remote-access tools Linux users take for granted. The MCP server opens a straightforward route for connecting sensor boards to AI agents. The new native_sim peripherals and VirtIO drivers make it practical to develop and test more code without hardware on the desk. The QEMU targets also let people try TriCore or Hexagon without buying an evaluation kit, once they have the TriCore QEMU and Hexagon toolchain pieces that are not yet in the SDK.

What to be careful with: mpipe is explicitly experimental, and its video and display elements are still under review. The 21% TCP figure comes from an emulated loopback benchmark, not from real hardware. Hardware-accelerated PSA Crypto covers only selected Silicon Labs, NXP and STM32 devices. Anyone upgrading an existing project should read the migration guide linked from the release notes and video description before moving across.

Price and availability: Zephyr 4.5.0 is released and available now as the v4.5.0 tag on the project's GitHub repository, published October 28, 2026. The sources quote no price; it is a software release, not a hardware product. SPDX 3.0 output requires selecting it with west spdx --spdx-version 3.0.

Sources