CVE-2021-34144
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 Bluetooth Classic implementation in the Zhuhai Jieli AC6366C BT SDK through 0.9.1 does not properly handle the reception of truncated LMP_SCO_Link_Request packets while no other BT connections are active, allowing attackers in radio range to prevent new BT connections (disabling the AB5301A inquiry and page scan procedures) via a crafted LMP packet. The user needs to manually perform a power cycle (restart) of the device to restore BT connectivity.
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 · high confidenceThe Zhutai Jieli AC6366C Bluetooth Classic implementation fails to properly validate truncated LMP_SCO_Link_Request packets when no active BT connections exist. An attacker within radio range can send a specially crafted malformed LMP packet that causes the Bluetooth controller to disable inquiry and page scan procedures, preventing legitimate devices from discovering or connecting to the affected device. The device requires a manual power cycle to restore Bluetooth functionality.
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<= 0.9.1CVSS 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
- Adjacent
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:A/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.
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Identify the Bluetooth chip modelInspect the device hardware or firmware documentation to determine if the Bluetooth controller is a Zhutai Jieli AC6366C chip. Look for chip markings or check the bill of materials.Affected if The device does not use the AC6366C chip, then it is not affected by this specific vulnerability.
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Determine the BT SDK firmware versionAccess the device firmware or SDK version information. This may be found in firmware metadata, boot logs, or device specification sheets. Look for version information labeled as 'Zh Jieli Fw Ac63 Bt Sdk' or similar.Affected if The installed firmware version is 0.9.1 or lower, indicating the device falls within the affected version range.
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Verify Bluetooth inquiry scan statusIf you have access to the Bluetooth stack or controller diagnostics, check whether inquiry scan is currently enabled. On some devices, this can be queried via HCI commands or seen in the BT stack logs.Affected if Inquiry scan has been disabled without explicit user action, which may indicate the vulnerability has been triggered.
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Verify Bluetooth page scan statusCheck the page scan configuration through Bluetooth controller diagnostics, HCI interfaces, or firmware debug logs. Confirm whether page scan is active.Affected if Page scan is disabled and cannot be re-enabled through software, which may indicate the exploit has been successful.
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Check for BT stack state changesReview any available system logs, Bluetooth stack logs, or firmware debug output for entries related to LMP_SCO_Link_Request packet processing or errors in packet validation.Affected if Logs show malformed LMP packet handling errors or indicate the Bluetooth controller entered an error state.
The device is affected if it uses the AC6366C chip with Zh Jieli Fw Ac63 Bt Sdk version 0.9.1 or lower, and Bluetooth inquiry or page scan has become disabled without manual user intervention.
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 input validation and bounds checking for all incoming LMP packets, ensuring truncated or malformed packets are rejected without affecting the Bluetooth stack state. Add error handling to prevent the inquiry/page scan procedures from being disabled upon receipt of malformed LMP_SCO_Link_Request packets.
- Consultation4.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-34144 — 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-2021-34144 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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- Version or environment caveats, and links to real fixes
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