CVE-2021-31611: The Bluetooth Classic implementation on Zhuhai Jieli AC690X and AC692X devices does not properly handle an out

Routine

MEDIUM 5.7MITIGATEMITIGATEMITIGATE

CVE-2021-31611 is a medium-severity flaw (CVSS 5.7) affecting ac6901 firmware, ac6925 firmware, ac6926 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The Bluetooth Classic implementation on Zhuhai Jieli AC690X and AC692X devices does not properly handle an out-of-order LMP Setup procedure that is followed by a malformed LMP packet, allowing attackers in radio range to deadlock a device via a crafted LMP packet. The user needs to manually reboot the device to restore communication.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	5.7 (Medium)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.4% (top 70%)
CISA exploited list	No
Weakness	CWE-667
Published	2021-09-07
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: zh-jieli

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

zh-jieli ac6901 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.

zh-jieli ac6925 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.

zh-jieli ac6926 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.

zh-jieli ac6928 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.

zh-jieli ac6921 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-2021-31611?

ac6901 firmware: mitigate or apply the listed mitigation; ac6925 firmware: mitigate or apply the listed mitigation; ac6926 firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-31611 being exploited?

CVE-2021-31611 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-2021-31611 affect?

CVE-2021-31611 affects ac6901 firmware, ac6925 firmware, ac6926 firmware. Severity is medium (CVSS 5.7). The Bluetooth Classic implementation on Zhuhai Jieli AC690X and AC692X devices does not properly handle an out-of-order LMP Setup procedure that is followed by a malformed LMP packet, allowing attackers in radio range to deadlock a device v

How urgent is CVE-2021-31611?

Priority 28/100. No elevated risk signals yet.

Software pages

Bluetooth vulnerabilities

Related CVEs

CVE-2021-31613 MEDIUM 6.5 MITIGATE MITIGATE The Bluetooth Classic implementation on Zhuhai Jieli AC690X and AC692X devices does not properly handle the re
CVE-2021-31612 MEDIUM 6.5 MITIGATE MITIGATE The Bluetooth Classic implementation on Zhuhai Jieli AC690X devices does not properly handle the reception of

References

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