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ZephyrOperating system · Zephyrproject

CVE-2023-1901

HIGH · 8.0 CVSS v3.1 Published 2023-07-10
Fix available
A fix is available. Upgrade to after 3.3.0 or later.
See remediation →
82/100
Remediation priority · High
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
The bluetooth HCI host layer logic not clearing a global reference to a semaphore after synchronously sending HCI commands may allow a malicious HCI Controller to cause the use of a dangling reference in the host layer, leading to a crash (DoS) or potential RCE on the Host layer.

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

In the Bluetooth HCI host layer, a global reference to a semaphore is not properly cleared after synchronously sending HCI commands. A malicious HCI Controller can exploit this to create a dangling reference, leading to use-after-free conditions that cause denial of service or potentially remote code execution on the host.

MitigationApply vendor patches for the affected Bluetooth stack implementation; ensure HCI Controller firmware is from trusted sources to mitigate malicious controller attacks.

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:L/PR:L/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. Check Zephyr version
    Identify the Zephyr RTOS version in your build by examining version files, git tags, or the Kconfig CONFIG_ZEPHYR_VERSION setting. Common locations: zephyr/.version, version file in build directory, or Kconfig.
    Affected if The installed Zephyr version is 3.3.0 or lower.
  2. Verify Bluetooth support is enabled
    Check your build configuration (prj.conf, defconfig, or .config) for CONFIG_BT=y or CONFIG_BT_HOST=y. Also verify the Bluetooth stack is compiled in your firmware image.
    Affected if Bluetooth host stack (BT_HOST) is enabled in the build configuration.
  3. Confirm HCI host layer is in use
    Check for the presence of Bluetooth HCI source files in your build, particularly hci_core.c or equivalent HCI host implementation. Look for CONFIG_BT_HCI_HOST in your configuration.
    Affected if The HCI host layer code is compiled into the firmware.
  4. Identify synchronous HCI command usage
    Examine application code for calls to bt_hci_cmd_send() or similar synchronous HCI command functions that wait for command complete events. Check for bt_hci_cmd_send_sync() or equivalent synchronous command APIs.
    Affected if The application uses synchronous HCI command functions that rely on semaphores for completion signaling.

A system is affected if it runs Zephyr version 3.3.0 or earlier with Bluetooth HCI host enabled and uses synchronous HCI command operations, as the dangling semaphore reference can only occur under these conditions.

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

Apply vendor patches for the affected Bluetooth stack implementation; ensure HCI Controller firmware is from trusted sources to mitigate malicious controller attacks.

Recommended fix Moderate confidence

Zephyr > 3.3.0 (specific fixed release version to be confirmed from Zephyr project release notes/GitHub)

  1. 1. Identify the current Zephyr version in use by checking the west manifest or version.h file
  2. 2. Obtain the latest Zephyr source from the official repository (github.com/zephyrproject-rtos/zephyr)
  3. 3. Review the Zephyr release notes for versions greater than 3.3.0 to identify the version containing the CVE-2023-1901 fix
  4. 4. Update the West manifest to point to the fixed version
  5. 5. Run 'west update' to fetch the new version
  6. 6. Rebuild and test the application with the updated Zephyr version
  7. 7. Verify the fix addresses the bluetooth HCI host layer semaphore dangling reference issue
Caveat Check Zephyr release notes between current version and target version for any breaking changes to bluetooth HCI APIs or configuration requirements

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

Fix this in Zephyr Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA6.0 h
30.0 hours of engineering $5,120
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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-2023-1901 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