CVE-2021-34147Public exploit

Adjacent device crash via malformed timing responses

Published Sep 7, 2021 · Updated Aug 4, 2024

Denial of service in the Cypress WICED BT stack 2.9.0 and earlier allows physically proximate attackers to crash CYW20735B1 devices. The Bluetooth Classic Link Manager mishandles a malformed LMP timing accuracy response across rapid reconnections, exhausting Bluetooth resources. The attack requires radio proximity and the target BDAddress but no pairing or authentication; the watchdog restarts the chip after a fault.

CVSS severity6.5
Medium
EPSS probability0.58%
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 the Cypress WICED BT stack 2.9.0 and earlier allows physically proximate attackers to crash CYW20735B1 devices. The Bluetooth Classic Link Manager mishandles a malformed LMP timing accuracy response across rapid reconnections, exhausting Bluetooth resources. The attack requires radio proximity and the target BDAddress but no pairing or authentication; the watchdog restarts the chip after a fault.

The record

CVE
CVE-2021-34147
Published
Sep 7, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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

6.5NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.1NIST NVDAV:A/AC:L/Au:N/C:N/I:N/A:C

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.

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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

T1499Endpoint Denial of Service

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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