CVE-2021-46840
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 HW_KEYMASTER module has an out-of-bounds access vulnerability in parameter set verification.Successful exploitation of this vulnerability may cause malicious construction of data, which results in out-of-bounds access.
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 · moderate confidenceThe HW_KEYMASTER module, which handles cryptographic key operations in Android's TrustZone secure environment, contains an out-of-bounds access vulnerability in its parameter set verification logic. An attacker could exploit this by crafting malicious parameters that bypass validation checks, allowing memory access beyond allocated buffers.
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= 11.0.1= 12.0.0= 2.0CVSS 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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 device manufacturer and modelCheck the device settings to confirm it is a Huawei device running Emui or HarmonyOSAffected if Device is a Huawei device running Emui or HarmonyOS
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Check Emui versionNavigate to Settings > About Phone > Version on Huawei devices. Look for EMUI version listed as 11.0.1 or 12.0.0Affected if EMUI version is exactly 11.0.1 or 12.0.0
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Check HarmonyOS versionNavigate to Settings > About Phone > Version on Huawei devices. Look for HarmonyOS version listed as 2.0Affected if HarmonyOS version is exactly 2.0
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Verify Keymaster module presenceCheck system logs or /vendor/etc/hw_keymaster*.xml configuration files if accessible via adb shell with root privileges. Confirm the HW_KEYMASTER module is loaded and handling key operationsAffected if HW_KEYMASTER module is loaded and active on the device
A device is affected only if it is a Huawei device running exactly Emui 11.0.1, Emui 12.0.0, or HarmonyOS 2.0 with the HW_KEYMASTER module active.
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 vendor-supplied firmware/security patch for the HW_KEYMASTER module. Given the critical severity (CVSS 9.1), prioritize patching on affected devices and verify the fix does not introduce regressions in secure key operations.
- Consultation8.0 h
- Implementation4.0 h
- Testing16.0 h
- Review / QA8.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $9,856.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-46840 — 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-2021-46840 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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- 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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