HOMEVULNERABILITIESCVE-2021-34147
MEDIUM

CVE-2021-34147

NVD-CWE-noinfoPublished: September 7, 2021· Updated: Jun 17, 2026

6.5
CVSS v3.1

Official Description

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.

NVD Source

Technical Analysis

CVE-2021-34147 requires adjacent network access, limiting remote exploitation but still posing risk in shared or local network environments.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorAdjacent
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

cypress2 product(s)
wireless internet connectivity for embedded devicescyw20735b1
Source: NVD CPE · 2 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://dl.packetstormsecurity.net/papers/general/braktooth.pdf
ADVISORYhttps://www.cypress.com/documentation/datasheets/cyw20735b1-single-chip-bluetooth-transceiver-wireless-input-devices
ADVISORYhttps://dl.packetstormsecurity.net/papers/general/braktooth.pdf
ADVISORYhttps://www.cypress.com/documentation/datasheets/cyw20735b1-single-chip-bluetooth-transceiver-wireless-input-devices

All References (4)

→
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

Quick Facts

CVE IDCVE-2021-34147
CVSS Score6.5 / 10
SeverityMEDIUM
WeaknessNVD-CWE-noinfo
CISA KEVNo
Affected1 vendor(s)
PublishedSep 7, 2021

Related CVEs (NVD-CWE-noinfo)

CVE-2018-4872
10.0
CVE-2018-2611
10.0
CVE-2017-10151
10.0
CVE-2017-10269
10.0
CVE-2017-14378
10.0
CVE-2018-4091
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-34147 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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