CVE-2021-34148

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 devices does not properly handle the reception of LMP_max_slot with a greater ACL Length after completion of the LMP setup procedure, allowing attackers in radio range to trigger a denial of service (firmware crash) via a crafted LMP packet.

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%Down 0.2 points since Sep 7, 2021

What each source reports

NVD Score used 6.5

Record: CVE-2021-34148
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

Record: CVE-2021-34148
Updated: 2026-11-02

EUVDEUVD-2021-20810 No score

Record: EUVD-2021-20810
Updated: 2026-11-03

GitHub AdvisoriesGHSA-6539-6fh5-h34x No score

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

Record: GHSA-6539-6fh5-h34x
Updated: 2026-11-02

OSV 6.5

Record: CVE-2021-34148
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-2021-34148 6.5

Record: DEBIAN-CVE-2021-34148
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-2021-34148 6.5

Record: UBUNTU-CVE-2021-34148
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

cypress wireless internet connectivity for embedded devices

Affected packages

Affected packages
Package	Affected	Fixed
`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
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

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

In short

CVE-2021-34148 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.