CVE-2021-3432

Bluetooth interruption via zero CONNECT_IND interval

Published Jun 28, 2022 · Updated Sep 17, 2024

Divide-by-zero in Zephyr RTOS 1.14.0 and later, before 2.6.0, allows physically proximate attackers to interrupt Bluetooth operation. The ull_slave_setup function accepted a zero CONNECT_IND interval and continued connection setup, allowing subsequent controller arithmetic to divide by zero. A nearby Bluetooth Low Energy initiator needs no authentication or user interaction; the bounded consequence is a service interrupt.

CVSS severity7.5
High
EPSS probability0.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Divide-by-zero in Zephyr RTOS 1.14.0 and later, before 2.6.0, allows physically proximate attackers to interrupt Bluetooth operation. The ull_slave_setup function accepted a zero CONNECT_IND interval and continued connection setup, allowing subsequent controller arithmetic to divide by zero. A nearby Bluetooth Low Energy initiator needs no authentication or user interaction; the bounded consequence is a service interrupt.

The record

CVE
CVE-2021-3432
Published
Jun 28, 2022
Updated
Sep 17, 2024
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-369, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 28, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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?

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  1. Affected versionversion=v1.14.0 <unspecified
  2. Affected versionversion=v2.5.0 <unspecified

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=v1.14.0 <unspecified; version=v2.5.0 <unspecified

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
4.3Zephyr ProjectCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-369Divide By Zero
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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