MCUboot in Zephyr firmware: identifiers and CRA notes

What it is

MCUboot

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Notes on this component

MCUboot, the secure bootloader that checks and installs firmware updates; it is built separately from the application, so an SBOM of the application alone does not list it. Flaws are published as GitHub security advisories on mcu-tools/mcuboot: CVE-2024-32883 / GHSA-m59c-q9gq-rh2j (the TLV parser does not distinguish entries that must be covered by the image signature from those that need not be, so an attacker can inject an unprotected dependency or boot-record entry that should have been protected, which can make an image appear to have properties it does not have; versions below 1.11.0 — the advisory still records the patch as in progress, so no fixed release is named), CVE-2021-3890 / GHSA-8hrv-4cp5-4rg3 (with MCUBOOT_MEASURED_BOOT set, the IMAGE_TLV_BOOT_RECORD length is checked only against the upper bound of the receiving buffer and not against the expected length; 1.7.0 up to 1.10) and CVE-2021-3399 / GHSA-gcxh-546h-phg4 (the development signing keys shipped in the repository are easy to ship in a product by accident; through 1.7.0, improved in 1.8.0). NVD has no CPE for MCUboot, so none of the three can be matched by CPE.

Also a subsystem, switched on by CONFIG_BOOTLOADER_MCUBOOT. MCUboot, the secure bootloader. This symbol means the application image was built to be chainloaded by MCUboot — it does NOT mean MCUboot itself is in this SBOM, because MCUboot is built separately and `west spdx` does not cover it. That gap is the point of the row: the bootloader is the root of trust for every update, and its SBOM has to be asked for. CVE family is image validation — signature and TLV parsing in the verification path — where a bug defeats secure boot entirely. MCUboot publishes its advisories on its own repository: CVE-2021-3399 (critical: the project's hard-coded development signing keys were easy to ship in a product, affecting 1.7.0 and earlier, mitigated in 1.8.0), CVE-2021-3890 (an unchecked boot-record TLV length underflows in the measured-boot path, affecting 1.7.0 and later versions before 1.10) and CVE-2024-32883 (high: unprotected TLV entries that should be signed could be injected, fixed in 1.11.0). Those are all three it has published as of 10 October 2026. NVD has no CPE for MCUboot under any vendor (its CPE dictionary, queried 11 October 2026, returned 0 entries for `mcuboot`), so this row carries none and its CVEs will not be matched from it; a maker has to watch MCUboot's own advisories. Version comes from the mcuboot module when the build carries it, and is otherwise unknown.

Where it hides in a firmware SBOM

Zephyr lists a west module by its west name, with no PURL or CPE. Vulnerability feeds cannot find it from that listing alone, which is why the SBOM check adds the identifiers below.

It is compiled into the kernel image when CONFIG_BOOTLOADER_MCUBOOT is y. It does not appear in west spdx output; the only trace is the .config file in your build directory.

The identifiers we assign

PURLpackage URL: a standard way to name a software package

pkg:github/mcu-tools/mcuboot@{version}

{version} is filled in from your build. The version is read from the upstream release tag.

The SBOM check adds these identifiers to a component your build listed without them.

Honest gaps

Vendor: mcu-tools.

This row has no CPE.

Where this row comes from

https://github.com/mcu-tools/mcuboot/security/advisories/GHSA-m59c-q9gq-rh2j
Checked on 10 October 2026.

Known vulnerabilities

Not checked yet

Vulnerability data changes daily. Check the version you ship in the SBOM check.

CRA notes

• List this component in your SBOM. Annex I, Part II (1): Identify and document components and vulnerabilities, including an SBOMKnow what is in your product. Identify and document its components and their vulnerabilities, including by producing a software bill of materials (SBOM) in a common machine-readable format that covers at least the top-level dependencies.
• Ship the version with no known exploitable vulnerabilities at release. Annex I, Part I (2(a)): Made available without known exploitable vulnerabilitiesWhen you place a release on the market, it must not ship with known vulnerabilities that can be exploited in your product. "Exploitable" means an attacker could effectively use it under practical operating conditions (Article 3(41)), not only in theory or in a lab. The Commission's draft guidance (C(2026) 5252, points 231 to 237; a draft, not binding) gives three ways a vulnerability is "known". One: it is listed in a relevant public vulnerability database, such as the European vulnerability database (EUVD) or another prominent one. Two: you learned of it from information that is not public, for example a security researcher's coordinated disclosure or your own testing and analysis; a vulnerability you know about and have not disclosed still counts. Three: it has been publicly and prominently reported in reliable media, whether specialist security publications or general news. A report is not yet proof: it does not by itself mean the vulnerability can be exploited in practice or applies to your product, so investigate promptly and confirm whether it does. A limited time may pass between the first report and that confirmation. If a vulnerability becomes known shortly before release, you decide from your cybersecurity risk assessment whether the release can go out or the vulnerability must be fixed first. Weigh its severity, exploitability and potential impact, and the risks to the product once in use; you may also weigh the risks of delaying the release, for example because it fixes other exploitable vulnerabilities. After release, the Part II vulnerability handling requirements still apply. Check your components against vulnerability databases before each release, and fix or justify what you find.
• A bootloader is part of how you deliver updates, so its update path matters here. Annex I, Part I (2(c)): Vulnerabilities can be fixed through security updatesVulnerabilities must be fixable through security updates. Where applicable, that includes automatic security updates that are switched on by default and install within an appropriate time, with a clear and easy-to-use way to opt out, together with telling users when an update is available and letting them postpone it for a while.

Source: Annex I of Regulation (EU) 2024/2847 (Cyber Resilience Act), legal state 2026.10.13-1.

Related Zephyr components

No related components yet.

Guides that mention MCUboot

• The CRA for Zephyr developers: what the law asks, what west spdx gives you, and what is left

Next step

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