CVE-2021-40009
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 · uneditedThere is an Out-of-bounds write vulnerability in the AOD module in smartphones. Successful exploitation of this vulnerability may affect service integrity.
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 · low confidenceAn out-of-bounds write vulnerability exists in the Always-On Display (AOD) module of smartphones. This memory corruption flaw allows writing data beyond allocated buffer boundaries, potentially enabling service integrity compromise. The attack vector appears to be local or adjacent, given the nature of smartphone module exploitation.
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< 2.0= 11.0.0= 12.0.0= 4.0.0CVSS 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
- None
- Integrity
- None
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 your Huawei OS versionGo to Settings > About Phone > Version on your Huawei device. Note whether it reports HarmonyOS, EMUI, or Magic UI and the specific version number displayed.Affected if The OS is HarmonyOS version below 2.0, EMUI 11.0.0 or 12.0.0, or Magic UI 4.0.0.
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Confirm the exact EMUI or Magic UI buildIn Settings > About Phone > Version, look for the build number. EMUI 11.0.0 and 12.0.0 are specifically listed as affected; other EMUI minor versions may differ.Affected if The build shows exactly EMUI 11.0.0 or EMUI 12.0.0.
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Verify HarmonyOS version if applicableIf HarmonyOS is installed, check if the version is below 2.0 by viewing the version number in Settings > About Phone.Affected if HarmonyOS version is below 2.0 (for example, 1.x).
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Check if Always-On Display is enabledGo to Settings > Display > Always-On Display (or Settings > Wallpaper > Always-On Display on some models) and verify whether the feature toggle is turned on.Affected if Always-On Display is currently enabled on the device.
You are affected if your device runs HarmonyOS below 2.0, EMUI 11.0.0, EMUI 12.0.0, or Magic UI 4.0.0 AND has Always-On Display enabled.
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 data2.0
Apply vendor-specific security patches for the AOD module once available; until then, minimize exposure by disabling AOD functionality and restricting device access to trusted users.
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA6.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $11,776.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-40009 — 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-2021-40009 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
- No spam, self-promotion, credentials, or personal data