CVE-2021-31786
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 Audio implementation on Actions ATS2815 and ATS2819 devices does not properly handle a connection attempt from a host with the same BDAddress as the current connected BT host, allowing attackers to trigger a disconnection and deadlock of the device by connecting with a forged BDAddress that matches the original connected host.
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 Bluetooth Classic Audio implementation on Actions ATS2815 and ATS2819 chipsets fails to properly handle simultaneous connection attempts from hosts claiming the same BDAddress as an already-connected host. An attacker can forge a BDAddress matching the legitimate connected host to trigger a disconnection and deadlock condition in the device.
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 dataall versionsall versionsall versionsall versionsall versionsCVSS 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 chipset in useCheck device hardware specifications, Bluetooth adapter details, or system information to determine the manufacturer and model of the Bluetooth chipset. For embedded devices, review the bill of materials or schematics.Affected if The device uses an Actions Semi ATS2815 or ATS2819 series chipset (including Ats2819p, Ats2819, Ats2819s, or Ats2819t variants)
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Confirm the chipset firmware versionAccess the Bluetooth firmware version through device diagnostics, Bluetooth stack logs, or manufacturer-provided tooling. On some platforms, this may appear in adapter properties or via commands like 'hcitool -V' or vendor-specific utilities.Affected if The firmware version is any version on the affected ATS2815/ATS2819 chipsets - all versions are vulnerable
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Verify active Bluetooth Classic Audio connectionsMonitor for active A2DP, HFP, or other Classic Audio profiles. Use Bluetooth host stack tools (such as 'btmon', 'hcidump', or platform-specific Bluetooth diagnostics) to list current connections and their BDAddresses.Affected if A device with one of these chipsets has an active Bluetooth Classic Audio connection that could be targeted for BDAddress spoofing
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Check for deadlock or disconnection anomaliesObserve the Bluetooth subsystem for unexpected disconnections or hangs, particularly when multiple connection requests to the same BDAddress may occur. Review system logs for BT stack errors or firmware crash indicators.Affected if The device exhibits frequent Bluetooth disconnections or becomes unresponsive when multiple hosts attempt connections using the same BDAddress
A user is affected if their device incorporates an Actions Semi ATS2815 or ATS2819 series Bluetooth chipset with any firmware version, as all such firmwares contain the BDAddress collision handling flaw.
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 dataApply vendor-provided firmware updates for the ATS2815/ATS2819 chipsets that address BDAddress collision handling; if unavailable, implement network access controls to prevent attackers from spoofing the legitimate BT host's BDAddress.
- Consultation6.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-31786 — 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-2021-31786 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
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