LZ4 in Zephyr firmware: identifiers and CRA notes

What it is

LZ4

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Notes on this component

LZ4, a very fast compression library. Zephyr dropped the module after v3.4.0 (the last `west.yml` that lists it), so it appears only in builds of Zephyr 3.4 or older. Flaws are filed in NVD under lz4_project:lz4; the project's GitHub security advisories list is empty, so a GHSA-only check finds nothing. Two are filed: CVE-2021-3520 (a crafted input overflows an integer and calls memmove() with a negative size, writing out of bounds; 1.8.3 up to 1.9.4, fixed in 1.9.4) and CVE-2019-17543 (a heap buffer overflow in LZ4_write32, reached through LZ4_compress_fast with a large input, which the maintainer notes affects only a few uncommon uses of the API; before 1.9.2). Because a Zephyr 3.4 or older build pins whatever commit the module was at, the 1.9.4 fix is the one to check the commit against.

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.

The identifiers we assign

PURLpackage URL: a standard way to name a software package

pkg:github/lz4/lz4@{version}

CPEthe product name vulnerability databases use to say what a flaw affects

cpe:2.3:a:lz4_project:lz4:{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: lz4_project.

Where this row comes from

https://nvd.nist.gov/vuln/detail/CVE-2021-3520
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.

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 LZ4

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

Next step

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