nRF Connect SDK fork of Mbed TLS in Zephyr firmware: identifiers and CRA notes

What it is

nRF Connect SDK fork of Mbed TLS

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Notes on this component

`upstream.vendor` is `arm`, the CPE's own upstream vendor, not Nordic Semiconductor: Nordic's SDK vendors a fork of Arm's project, and a generated SBOM should name the fork's real upstream as supplier (`components[].supplier`), not the SDK that merely carries it. NCS's fork of Mbed TLS, at `repo-path: sdk-mbedtls`, `path: modules/crypto/mbedtls` — a second fork on top of Zephyr's own (the plain `mbedtls` row), carrying Nordic's PSA driver glue for the CryptoCell and Oberon back ends. A build may link this fork and still do its actual cryptographic operations through `nordic-cc3xx-crypto`'s precompiled driver, so an Mbed TLS version alone does not describe what signs or decrypts anything on a Nordic part. The upstream advisories are filed under arm:mbed_tls and trustedfirmware:mbed_tls and the fork is not tracked separately; the most serious are CVE-2026-34877 (a modified serialized SSL session or context induces memory corruption and can reach arbitrary code execution; 2.19.0 through 3.6.5), CVE-2026-34873 (client impersonation on TLS 1.3 session resumption; 3.5.0 through 4.0.0) and CVE-2026-25833 (a buffer overflow in x509_inet_pton_ipv6(); 3.5.0 through 3.6.5), all three fixed upstream in 3.6.6. Whether this fork has taken the 3.6.6 fixes was NOT checked for this row: Nordic publishes no advisory feed for sdk-mbedtls, and the ncs-vX tag a build pins does not state which upstream version it merged. That tag is the SDK's release number, not an Mbed TLS version: at `ncs-v3.4.0` the fork's `include/mbedtls/build_info.h` says Mbed TLS 4.1.0 (github.com/nrfconnect/sdk-mbedtls/blob/ncs-v3.4.0/include/mbedtls/build_info.h, read 11 October 2026). A west manifest does not carry that file, so no Mbed TLS version is read from such a tag.

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/nrfconnect/sdk-mbedtls@{version}

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

cpe:2.3:a:arm:mbed_tls:{version}:*:*:*:*:*:*:*

{version} is filled in from your build. The version is read from a version file in the upstream source.

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

Honest gaps

Vendor: arm.

Where this row comes from

https://nvd.nist.gov/vuln/detail/CVE-2026-34877
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 nRF Connect SDK fork of Mbed TLS

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

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