CVE-2021-31611Public exploit

Bluetooth deadlock via invalid LMP setup sequence

Published Sep 7, 2021 · Updated Aug 3, 2024

Denial of service in Zhuhai Jieli AC690X and AC692X Bluetooth Classic firmware allows physically proximate attackers to deadlock devices. The link manager processes a duplicated LMP_setup_complete followed by an LMP_features_req_ext carrying invalid opcode 0x64 instead of rejecting the sequence. No pairing or authentication is required; on single-connection products, the attack is reachable only while no user device is connected, and recovery requires a manual reboot.

CVSS severity5.7
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Zhuhai Jieli AC690X and AC692X Bluetooth Classic firmware allows physically proximate attackers to deadlock devices. The link manager processes a duplicated LMP_setup_complete followed by an LMP_features_req_ext carrying invalid opcode 0x64 instead of rejecting the sequence. No pairing or authentication is required; on single-connection products, the attack is reachable only while no user device is connected, and recovery requires a manual reboot.

The record

CVE
CVE-2021-31611
Published
Sep 7, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-667, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

3.3NIST NVDAV:A/AC:L/Au:N/C:N/I:N/A:P
5.7NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-667Improper Locking
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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