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ZephyrOperating system · Zephyrproject

CVE-2021-3432

HIGH · 7.5 CVSS v3.1 Published 2022-06-28
Fix available
A fix is available. Upgrade to 2.6.0 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Invalid interval in CONNECT_IND leads to Division by Zero. Zephyr versions >= v1.14.0 Divide By Zero (CWE-369). For more information, see https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-7364-p4wc-8mj4

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A division-by-zero vulnerability exists in the Zephyr RTOS Bluetooth stack where an invalid interval field in a CONNECT_IND packet is used as a divisor without validation. When a malformed CONNECT_IND message with a zero or invalid interval is received during BLE connection establishment, the affected code attempts to divide by this value, causing a crash or denial of service.

MitigationUpgrade Zephyr to a version that includes the fix for this vulnerability, or apply the relevant patch that adds validation of the interval field in CONNECT_IND handling before performing division operations.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
ZephyrOperating system
Affected:>= 1.14.0, < 2.6.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the Zephyr version in use
    Check the kernel version by inspecting the build configuration file (usually .config or defconfig) for CONFIG_ZEPHYR_VERSION, or look at the version header file typically found at include/zephyr/version.h in the Zephyr source tree
    Affected if The version is >= 1.14.0 and < 2.6.0 (the vulnerable version range)
  2. Confirm Bluetooth stack is enabled
    Inspect the build configuration for CONFIG_BLUETOOTH=y or CONFIG_BT=y. This is typically found in the project's prj.conf, defconfig, or the generated .config file
    Affected if Bluetooth is enabled (CONFIG_BLUETOOTH or CONFIG_BT is set)
  3. Verify BLE connection roles are in use
    Check the configuration for CONFIG_BT_CENTRAL=y or CONFIG_BT_PERIPHERAL=y (or both). These roles involve receiving CONNECT_IND packets during connection establishment
    Affected if Either central or peripheral BLE role is enabled (these roles receive and process CONNECT_IND packets)
  4. Inspect CONNECT_IND handling code for interval validation
    Examine the source file handling BLE CONNECT_IND packets in the Bluetooth host stack (typically in subsys/bluetooth/host/conn.c or similar). Look for the code that processes the connection interval field and verify whether a validation check exists before the division operation
    Affected if The code lacks validation of the interval field before performing division, or the specific fix commit (commit reference in Zephyr repo) is not applied

You are affected if your Zephyr version is between 1.14.0 and 2.6.0, Bluetooth is enabled, and the interval field validation is missing from the CONNECT_IND handler code.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.6.0 or later
Fixed in 2.6.0
Interim mitigation

Upgrade Zephyr to a version that includes the fix for this vulnerability, or apply the relevant patch that adds validation of the interval field in CONNECT_IND handling before performing division operations.

Recommended fix Moderate confidence

2.6.0

  1. 1. Identify all deployed instances of Zephyr with versions >= 1.14.0 and < 2.6.0
  2. 2. Review the Zephyr release notes and migration guide for version 2.6.0
  3. 3. Update the Zephyr version to 2.6.0 or later in the project configuration
  4. 4. Rebuild and test the application to ensure compatibility with the new version
  5. 5. Redeploy the updated firmware to all affected devices

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Zephyr Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,560
Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-3432 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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