CVE-2021-40035
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 Buffer overflow vulnerability due to a boundary error with the Samba server in the file management module in smartphones. Successful exploitation of this vulnerability may affect function stability.
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 buffer overflow vulnerability exists in the Samba server component within the file management module of smartphones. The flaw is caused by a boundary error, allowing an attacker to potentially overwrite adjacent memory and impact function stability. This appears to be a server-side vulnerability in the SMB/CIFS file sharing implementation.
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= 10.0.0= 10.1.0= 10.1.1= 11.0.0= 11.0.1= 12.0.0= 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
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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.
-
Identify device model and OSCheck the smartphone settings to determine the device model and the installed operating system (HarmonyOS, EMUI, or Magic UI)Affected if The device is a Huawei smartphone running HarmonyOS, EMUI, or Magic UI
-
Check HarmonyOS versionNavigate to Settings > About Phone > Version on HarmonyOS devices and compare the version number to the affected range (< 2.0)Affected if The HarmonyOS version is below 2.0
-
Check EMUI versionNavigate to Settings > About Phone > Version on EMUI devices and compare the exact version to the affected list (10.0.0, 10.1.0, 10.1.1, 11.0.0, 11.1.0, 12.0.0)Affected if The EMUI version exactly matches one of the listed affected versions
-
Check Magic UI versionNavigate to Settings > About Phone > Version on Magic UI devices and compare the exact version to the affected list (3.0.0, 3.1.0, 3.1.1, 4.0.0)Affected if The Magic UI version exactly matches one of the listed affected versions
-
Verify SMB file sharing is enabledCheck if the Samba/SMB/CIFS file sharing service is active on the device, typically found under Settings > Network & Internet > Mobile Network Sharing or Settings > Connections > File SharingAffected if SMB file sharing is currently enabled on the device
A user is affected if their Huawei smartphone runs the specific vulnerable OS version (HarmonyOS < 2.0, EMUI 10.0.0/10.1.0/10.1.1/11.0.0/11.1.0/12.0.0, or Magic UI 3.0.0/3.1.0/3.1.1/4.0.0) AND has SMB file sharing service 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-provided security patches for the affected smartphone firmware. If no patch is available, disable file sharing services or restrict network access to trusted endpoints to reduce exposure.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,888.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-40035 — 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-2021-40035 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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