CVE-2021-39981
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 · uneditedChang Lian application has a vulnerability which can be maliciously exploited to hide the calling number.Successful exploitation of this vulnerability allows you to make an anonymous call.
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 Chang Lian phone application contains a vulnerability that allows malicious actors to hide or spoof their calling number, enabling anonymous calls. This appears to be a logic flaw in how the application validates and presents caller ID information to the receiving party. The vulnerability likely stems from insufficient validation of caller ID parameters passed through the application to the telephony layer.
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= 2.0CVSS 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
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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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Confirm HarmonyOS versionNavigate to Settings > About Phone on the Huawei device and verify the OS version is exactly 2.0Affected if The device runs HarmonyOS version 2.0
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Identify Chang Lian applicationCheck the installed applications list in Settings > Apps > Apps to locate the Chang Lian phone applicationAffected if The Chang Lian phone application is installed on the device
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Review caller ID presentation settingsOpen the Chang Lian phone app, go to Settings or Call settings, and inspect any options related to Caller ID, Calling Number Display, or Number PresentationAffected if There is a setting that allows users to hide or manually specify the caller ID value
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Test caller ID manipulationAttempt to initiate a call while attempting to modify or suppress the caller ID through the application's call settings or API parametersAffected if The application permits caller ID to be hidden or spoofed without carrier-level enforcement
A user is affected if their device runs HarmonyOS 2.0 with the Chang Lian phone application installed and the app allows caller ID to be manipulated through its settings or parameters.
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 proper caller ID validation and enforcement at the application layer, ensuring that caller ID display cannot be bypassed or manipulated. Additionally, enforce carrier-level caller ID presentation policies and reject any requests to suppress caller information unless explicitly authorized through legitimate carrier mechanisms.
- Consultation6.0 h
- Implementation12.0 h
- Testing10.0 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 $8,928.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39981 — 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-2021-39981 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
- No spam, self-promotion, credentials, or personal data