CVE-2021-31785: The Bluetooth Classic implementation on Actions ATS2815 and ATS2819 chipsets does not properly handle the rece

Routine

MEDIUM 6.5MITIGATEMITIGATEMITIGATE

CVE-2021-31785 is a medium-severity flaw (CVSS 6.5) affecting ats2819p firmware, ats2815 firmware, ats2819 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 62%)
CISA exploited list	No
Weakness	CWE-667
Published	2021-09-07
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: actions-semi

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-09-07 07:15 UTCPublished CVE record published
2026-06-17 03:52 UTCUpdated Record last modified

actions-semi ats2819p firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

actions-semi ats2815 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

actions-semi ats2819 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

actions-semi ats2819s firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

actions-semi ats2819t firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-31785?

ats2819p firmware: mitigate or apply the listed mitigation; ats2815 firmware: mitigate or apply the listed mitigation; ats2819 firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-31785 being exploited?

CVE-2021-31785 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-31785 affect?

CVE-2021-31785 affects ats2819p firmware, ats2815 firmware, ats2819 firmware. Severity is medium (CVSS 6.5). 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

How urgent is CVE-2021-31785?

Priority 32/100. No elevated risk signals yet.

Software pages

Bluetooth vulnerabilities

Related CVEs

CVE-2021-31787 MEDIUM 6.5 MITIGATE MITIGATE The Bluetooth Classic implementation on Actions ATS2815 chipsets does not properly handle the reception of con
CVE-2021-31786 MEDIUM 6.5 MITIGATE MITIGATE The Bluetooth Classic Audio implementation on Actions ATS2815 and ATS2819 devices does not properly handle a c

References

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