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CVE-2021-34147

The Bluetooth Classic implementation in the Cypress WICED BT stack through 2.9.0 for CYW20735B1...

6.5 MediumFix available

The Bluetooth Classic implementation in the Cypress WICED BT stack through 2.9.0 for CYW20735B1 does not properly handle the reception of a malformed LMP timing accuracy response followed by multiple reconnections to the link slave, allowing attackers to exhaust device BT resources and eventually trigger a crash via multiple attempts of sending a crafted LMP timing accuracy response followed by a sudden reconnection with a random BDAddress.

Attack profile

How easy it is to exploit

Attack vector
Adjacent network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.59%Unchanged since Sep 7, 2021
90%50%10%1%

What each source reports

NVD Score used 6.5

The Bluetooth Classic implementation in the Cypress WICED BT stack through 2.9.0 for CYW20735B1 does not properly handle the reception of a malformed LMP timing accuracy response followed by multiple reconnections to the link slave, allowing attackers to exhaust device BT resources and eventually trigger a crash via multiple attempts of sending a crafted LMP timing accuracy response followed by a sudden reconnection with a random BDAddress.

Record
CVE-2021-34147
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
6.1 MediumAV:A/AC:L/Au:N/C:N/I:N/A:C
Updated
2026-11-02
CVE List No score

The Bluetooth Classic implementation in the Cypress WICED BT stack through 2.9.0 for CYW20735B1 does not properly handle the reception of a malformed LMP timing accuracy response followed by multiple reconnections to the link slave, allowing attackers to exhaust device BT resources and eventually trigger a crash via multiple attempts of sending a crafted LMP timing accuracy response followed by a sudden reconnection with a random BDAddress.

Record
CVE-2021-34147
Updated
2026-11-02
EUVDEUVD-2021-20809 No score

The Bluetooth Classic implementation in the Cypress WICED BT stack through 2.9.0 for CYW20735B1 does not properly handle the reception of a malformed LMP timing accuracy response followed by multiple reconnections to the link slave, allowing attackers to exhaust device BT resources and eventually trigger a crash via multiple attempts of sending a crafted LMP timing accuracy response followed by a sudden reconnection with a random BDAddress.

Record
EUVD-2021-20809
Updated
2026-11-03
GitHub AdvisoriesGHSA-m739-9w4c-mx4g No score

The Bluetooth Classic implementation in the Cypress WICED BT stack through 2.9.0 for CYW20735B1...

The Bluetooth Classic implementation in the Cypress WICED BT stack through 2.9.0 for CYW20735B1 does not properly handle the reception of a malformed LMP timing accuracy response followed by multiple reconnections to the link slave, allowing attackers to exhaust device BT resources and eventually trigger a crash via multiple attempts of sending a crafted LMP timing accuracy response followed by a sudden reconnection with a random BDAddress.

Record
GHSA-m739-9w4c-mx4g
Updated
2026-11-02
OSV 6.5

The Bluetooth Classic implementation in the Cypress WICED BT stack through 2.9.0 for CYW20735B1 does not properly handle the reception of a malformed LMP timing accuracy response followed by multiple reconnections to the link slave, allowing attackers to exhaust device BT resources and eventually trigger a crash via multiple attempts of sending a crafted LMP timing accuracy response followed by a sudden reconnection with a random BDAddress.

Record
CVE-2021-34147
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2021-34147 6.5

The Bluetooth Classic implementation in the Cypress WICED BT stack through 2.9.0 for CYW20735B1 does not properly handle the reception of a malformed LMP timing accuracy response followed by multiple reconnections to the link slave, allowing attackers to exhaust device BT resources and eventually trigger a crash via multiple attempts of sending a crafted LMP timing accuracy response followed by a sudden reconnection with a random BDAddress.

Record
DEBIAN-CVE-2021-34147
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-34147 6.5

The Bluetooth Classic implementation in the Cypress WICED BT stack through 2.9.0 for CYW20735B1 does not properly handle the reception of a malformed LMP timing accuracy response followed by multiple reconnections to the link slave, allowing attackers to exhaust device BT resources and eventually trigger a crash via multiple attempts of sending a crafted LMP timing accuracy response followed by a sudden reconnection with a random BDAddress.

Record
UBUNTU-CVE-2021-34147
CVSS 3.1
6.5 MediumCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
bluez-firmware
Debian:12
before 1.2-8, plus listed versions
1.0-21.0-31.2-11.2-21.2-3
Show 6 moreShow less
1.2-41.2-51.2-61.2-71.2-7~bpo11+11.2-8~bpo11+1
1.2-8
bluez-firmware
Debian:13
before 1.2-8, plus listed versions
1.0-21.0-31.2-11.2-21.2-3
Show 6 moreShow less
1.2-41.2-51.2-61.2-71.2-7~bpo11+11.2-8~bpo11+1
1.2-8
bluez-firmware
Debian:14
before 1.2-8, plus listed versions
1.0-21.0-31.2-11.2-21.2-3
Show 6 moreShow less
1.2-41.2-51.2-61.2-71.2-7~bpo11+11.2-8~bpo11+1
1.2-8
bluez-firmware
Ubuntu:22.04:LTS
All versions, plus listed versions
1.2-7
None known

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-34147 is a medium vulnerability (CVSS 6.5) in Cypress Wireless Internet Connectivity For Embedded Devices, published September 7, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.59%, the 48th percentile. Fixed in bluez-firmware 1.2-8.

References

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