dbcve.org
Ats2819p FirmwareOperating system · Actions Semi

CVE-2021-31785

MEDIUM · 6.5 CVSS v3.1 Published 2021-09-07
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
70/100
Remediation priority · Elevated
No privileges Zero-click

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 · unedited
The Bluetooth Classic implementation on Actions ATS2815 and ATS2819 chipsets does not properly handle the reception of multiple LMP_host_connection_req packets, allowing attackers in radio range to trigger a denial of service (deadlock) of the device via crafted LMP packets. Manual user intervention is required to restart the device and restore Bluetooth communication.

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 confidence

The Actions ATS2815 and ATS2819 chipsets contain a flaw in their Bluetooth Classic (BR/EDR) stack where handling of the LMP_host_connection_req (Link Management Protocol) packet is insufficient. An attacker within radio range can send multiple crafted LMP_host_connection_req packets to trigger a deadlock in the Bluetooth firmware, causing complete loss of Bluetooth functionality until the device is manually power-cycled.

MitigationObtain and deploy a firmware patch from Actions Semiconductor addressing the LMP packet handling vulnerability. If no patch is available, replace affected devices with hardware containing an updated Bluetooth stack. Organizations should assess the operational criticality of devices using these chipsets and implement manual restart procedures as an interim contingency until remediation is possible.

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
Ats2819p FirmwareOperating system
Affected:all versions
Ats2815 FirmwareOperating system
Affected:all versions
Ats2819 FirmwareOperating system
Affected:all versions
Ats2819s FirmwareOperating system
Affected:all versions
Ats2819t FirmwareOperating system
Affected:all versions

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify devices using Actions Semi ATS2815 or ATS2819 chipsets
    Review hardware specifications, device BOMs, or use Bluetooth host controller interface (HCI) commands (e.g., hciconfig hci0, BR/EDR controller info) to identify the chipset vendor and model
    Affected if The device contains an Actions Semi Ats2815, Ats2819, Ats2819p, Ats2819s, or Ats2819t Bluetooth chipset
  2. Check the firmware version of the Actions Semi Bluetooth chipset
    Query the Bluetooth controller firmware version via HCI commands (e.g., hcitool -i hci0 version, or via bluetoothctl info). Compare the firmware version against the affected version ranges.
    Affected if Firmware version is present and matches any of the listed chipset variants (all versions of Ats2815, Ats2819, Ats2819p, Ats2819s, Ats2819t are affected)
  3. Verify Bluetooth Classic (BR/EDR) is enabled
    Check Bluetooth adapter status using system commands (e.g., rfkill list, hciconfig, or bluetoothctl show) to confirm BR/EDR mode is active
    Affected if Bluetooth BR/EDR mode is enabled and the device uses one of the affected chipsets
  4. Check for Bluetooth deadlock symptoms
    Test Bluetooth functionality by attempting device discovery (e.g., hcitool -i hci0 scan) and pairing. Observe if Bluetooth becomes unresponsive or fails to recover without power cycle.
    Affected if Bluetooth functionality is lost and requires manual power cycle to restore

A user is affected if their device contains any Actions Semi Ats2815, Ats2819, Ats2819p, Ats2819s, or Ats2819t chipset with Bluetooth BR/EDR enabled, as all firmware versions are vulnerable to the LMP packet handling deadlock.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Obtain and deploy a firmware patch from Actions Semiconductor addressing the LMP packet handling vulnerability. If no patch is available, replace affected devices with hardware containing an updated Bluetooth stack. Organizations should assess the operational criticality of devices using these chipsets and implement manual restart procedures as an interim contingency until remediation is possible.

Fix this in Ats2819p Firmware Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-31785 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-31785 in production — separate from our analysis above.

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.

What this is

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.

What belongs here
  • 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