CVE-2021-34148

Name: CVE-2021-34148
Creator: NVD / NIST
Published: 2021-09-07T07:15:07.42+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.56%

Last modified Jun 17, 2026

CVE-2021-34148 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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.. EPSS estimates a 0.56% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.56%

42.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Cypress	Wireless Internet Connectivity For Embedded Devices	<= 2.9.0

References

https://dl.packetstormsecurity.net/papers/general/braktooth.pdfTechnical Description, Third Party Advisory
https://www.cypress.com/documentation/datasheets/cyw20735b1-single-chip-bluetooth-transceiver-wireless-input-devicesVendor Advisory
https://dl.packetstormsecurity.net/papers/general/braktooth.pdfTechnical Description, Third Party Advisory
https://www.cypress.com/documentation/datasheets/cyw20735b1-single-chip-bluetooth-transceiver-wireless-input-devicesVendor Advisory

Timeline

Published: Sep 7, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-34148?

How severe is CVE-2021-34148?

CVE-2021-34148 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.56% probability of exploitation in the next 30 days.

How do I fix CVE-2021-34148?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-34148?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST