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ZephyrOperating system · Zephyrproject

CVE-2023-2234

HIGH · 8.8 CVSS v3.1 Published 2023-07-10
Fix available
A fix is available. Upgrade to after 3.3.0 or later.
See remediation →
93/100
Remediation priority · Urgent
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
Union variant confusion allows any malicious BT controller to execute arbitrary code on the Zephyr host.

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

This is a union variant confusion vulnerability in Zephyr RTOS's Bluetooth stack. A malicious or compromised BT controller can exploit this flaw to execute arbitrary code on the Zephyr host by manipulating union type handling in the HCI (Host Controller Interface) communication layer.

MitigationUpdate Zephyr RTOS to the version containing the security patch. If immediate patching is not feasible, implement network-level controls to ensure only trusted Bluetooth controllers can communicate with the Zephyr host.

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:<= 3.3.0

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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 Zephyr RTOS version
    Check the version of the Zephyr RTOS codebase or SDK used in your build system. This is typically found in the manifest file, version header (such as VERSION file), or the build configuration. Compare it against the affected version range: <= 3.3.0
    Affected if The installed Zephyr version is 3.3.0 or lower
  2. Confirm Bluetooth stack is enabled
    Review your Zephyr project configuration (prj.conf or Kconfig) for CONFIG_BT settings, specifically CONFIG_BT_HCI or related Bluetooth host options. Verify whether the Bluetooth stack is compiled into the firmware image
    Affected if Bluetooth/HCI functionality is enabled in the build configuration
  3. Check for external BT controller interface
    Inspect your hardware configuration and device tree to determine if the Zephyr device uses an external Bluetooth controller (e.g., separate BT chip connected via UART, USB, or SPI) rather than an integrated Bluetooth radio. Review board and device tree definitions for HCI transport bindings
    Affected if The Zephyr host communicates with an external, potentially untrusted Bluetooth controller via HCI
  4. Verify HCI data path exposure
    Examine the system's network and physical access controls to determine whether the Bluetooth controller interface could be accessed by an untrusted or compromised device. Check if the BT controller is in a trusted, controlled environment or if it could be replaced by a malicious device
    Affected if The HCI interface between Zephyr and the BT controller is accessible to untrusted or potentially compromised devices

A user is affected if they are running Zephyr RTOS version 3.3.0 or lower with Bluetooth/HCI enabled and using an external Bluetooth controller that could be malicious or compromised.

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 a release after 3.3.0
Interim mitigation

Update Zephyr RTOS to the version containing the security patch. If immediate patching is not feasible, implement network-level controls to ensure only trusted Bluetooth controllers can communicate with the Zephyr host.

Recommended fix Moderate confidence

Zephyr RTOS 3.4.0 or later stable release

  1. 1. Identify the Zephyr version currently in use by checking the manifest file (west.yml) or version.h header
  2. 2. Update the Zephyr manifest to reference a version newer than 3.3.0 (such as 3.4.0 or latest stable)
  3. 3. Run 'west update' to fetch the new version
  4. 4. Rebuild and test the application with the new Zephyr version
  5. 5. Verify the Bluetooth stack functions correctly after the upgrade
Caveat Potential API changes in Bluetooth stack or other subsystems between 3.3.0 and newer versions - review Zephyr release notes for migration details

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

Fix this in Zephyr Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA3.0 h
20.0 hours of engineering $3,420
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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-2023-2234 in production — separate from our analysis above.

No notes yet

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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
  • No spam, self-promotion, credentials, or personal data