FatFs in Zephyr firmware: identifiers and CRA notes

What it is

FatFs

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Notes on this component

FatFs by ChaN, a FAT filesystem driver. Upstream (elm-chan.org/fsw/ff) is a download, not a git repository, so Zephyr's own fork is the only history and a manifest gives a commit, not a release name such as R0.15a. NVD lists CVEs under elm-chan:fatfs, which this row sets without a version; upstream is not on GitHub, so there are no GitHub advisories. Six flaws were filed against R0.16 and earlier in July 2026, all reached through crafted on-disk metadata, which on a removable card is attacker-supplied: CVE-2026-6682 (`fasize *= fs->n_fats` wraps in mount_volume(), so callers go on to read with attacker-controlled lengths), CVE-2026-6687 (f_getlabel() trusts the exFAT label length XDIR_NumLabel without enforcing the spec maximum and overflows the stack) and CVE-2026-6688 (with long filenames enabled fno.fname can be 255 characters, and callers copy it into short fixed buffers without a bounds check). The other three are CVE-2026-6683, CVE-2026-6684 and CVE-2026-6686. No fixed release is named for the five that say "R0.16 and earlier"; CVE-2026-6684 is fixed in R0.16.

Also a subsystem, switched on by CONFIG_FAT_FILESYSTEM_ELM. ELM FatFs, vendored as a Zephyr module. CVE family is parsing of on-disk structures — boot sector, FAT and directory entries — which matters whenever the medium is removable or writable by another party, because that data is attacker-controlled. Upstream is ChaN's FatFs (elm-chan.org/fsw/ff/); no CPE is recorded because there is no established vendor:product pair, so matching uses the name and repository. One advisory is filed against the FAT back end in Zephyr: CVE-2020-13598, a buffer overflow in fs_stat when long file names are enabled, fixed in 2.4.0. None has been filed since, as of 9 October 2026 — but ChaN ships FatFs fixes as dated revisions rather than CVEs, so the module's own revision is the thing to check here, not this list alone.

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_FAT_FILESYSTEM_ELM 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/zephyrproject-rtos/fatfs@{version}

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

cpe:2.3:a:elm-chan:fatfs:*:*:*:*:*:*:*:*

{version} is filled in from your build. The version is pinned to the upstream commit your build uses.

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

Honest gaps

Vendor: elm-chan.

Where this row comes from

https://nvd.nist.gov/vuln/detail/CVE-2026-6682
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.
• An SBOM without this subsystem under-reports what is in the image. 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.

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 FatFs

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

Next step

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