CVE-2021-29415
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedThe elliptic curve cryptography (ECC) hardware accelerator, part of the ARM® TrustZone® CryptoCell 310, contained in the NordicSemiconductor nRF52840 through 2021-03-29 has a non-constant time ECDSA implemenation. This allows an adversary to recover the private ECC key used during an ECDSA operation.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe ECC hardware accelerator in ARM TrustZone CryptoCell 310 (used in Nordic Semiconductor nRF52840) implements ECDSA in non-constant time, creating a timing side-channel that leaks information about the private key during signatures. An attacker with precise timing measurements or power analysis capability can recover the ECDSA private key.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 2021-03-29CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify nRF52840 hardware in useLocate the device model number or bill of materials. Confirm the main MCU is Nordic Semiconductor nRF52840. Check product documentation or hardware markings.Affected if The device uses nRF52840 as the primary microcontroller.
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Check firmware version or build dateConnect to the device via debug interface (J-Link/RTT) or read firmware metadata. Determine the firmware version string or compilation timestamp.Affected if Firmware version is unknown, or firmware was built on or before 2021-03-29.
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Determine if ECDSA is usedReview application source code or binary for ECDSA-related function calls (such as ECDSA sign operations using CryptoCell APIs). Check if the application performs digital signature operations.Affected if The firmware uses ECDSA for signature operations.
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Confirm CryptoCell ECC accelerator is enabledReview project configuration (nRF5 SDK or nRF Connect config files) for settings that enable the CryptoCell hardware accelerator for ECC operations. Look for CRYPTO_ENABLED or similar flags.Affected if CryptoCell ECC accelerator is enabled in the firmware configuration.
A device is affected if it is an nRF52840 with firmware built on or before 2021-03-29 that uses the CryptoCell hardware accelerator for ECDSA operations.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply any vendor firmware updates from Nordic Semiconductor that address the CryptoCell timing vulnerability; if no patch is available, consider whether affected devices handle high-value keys requiring protection.
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $11,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-29415 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-29415 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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