CVE-2021-40055
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 a man-in-the-middle attack vulnerability during system update download in recovery mode. Successful exploitation of this vulnerability may affect 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 · moderate confidenceA man-in-the-middle vulnerability exists in the system update download mechanism when the device is in recovery mode. An attacker positioned on the same network can intercept and modify update packages during transit, potentially leading to installation of tampered firmware and compromised system integrity.
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= 10.0.0= 10.1.0= 10.1.1= 11.0.0= 11.0.1= 12.0.0= 2.0= 3.0.0= 3.1.0= 3.1.1= 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/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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Check the installed EMUI versionGo to Settings > About Phone > Version on the Huawei device and note the EMUI version number displayedAffected if The version shown is exactly 10.0.0, 10.1.0, 10.1.1, 11.0.0, 11.0.1, or 12.0.0
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Check the installed HarmonyOS versionGo to Settings > About Phone > Version on the Huawei device and note the HarmonyOS version number displayedAffected if The version shown is exactly 2.0
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Check the installed Magic UI versionGo to Settings > About Phone > Version on the Huawei device and note the Magic UI version number displayedAffected if The version shown is exactly 3.0.0, 3.1.0, 3.1.1, or 4.0.0
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Determine if device was recently in recovery modeCheck system update history in Settings > System > Update & Recovery or look for boot/recovery logs if availableAffected if The device has entered recovery mode and performed a system update while on an untrusted network
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Verify network conditions during recent updatesReview network logs or router history for any suspicious interception attempts during times when system updates were downloadedAffected if Update downloads occurred over unencrypted HTTP or on a network where man-in-the-middle attacks are possible
A device is affected only if it runs one of the listed exact versions, has been placed into recovery mode, and downloaded a system update over an untrusted or unencrypted network connection.
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 dataImplement TLS with proper certificate validation for all update downloads in recovery mode, or use code signing verification on the downloaded update packages before execution.
- Consultation2.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,480.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-40055 — 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-2021-40055 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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