CVE-2021-28136

Name: CVE-2021-28136
Creator: NVD / NIST
Published: 2021-09-07T06:15:07.33+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.81%

Last modified Jun 17, 2026

CVE-2021-28136 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. The Bluetooth Classic implementation in Espressif ESP-IDF 4.4 and earlier does not properly handle the reception of multiple LMP IO Capability Request packets during the pairing process, allowing attackers in radio range to trigger memory corruption (and consequently a crash) in ESP32 via a replayed (duplicated) LMP packet.. EPSS estimates a 0.81% chance of exploitation in the next 30 days.

Description

The Bluetooth Classic implementation in Espressif ESP-IDF 4.4 and earlier does not properly handle the reception of multiple LMP IO Capability Request packets during the pairing process, allowing attackers in radio range to trigger memory corruption (and consequently a crash) in ESP32 via a replayed (duplicated) LMP packet.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.81%

52.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-787

Affected Software

Vendor	Product	Versions
Espressif	Esp-Idf	<= 4.4

References

https://dl.packetstormsecurity.net/papers/general/braktooth.pdfTechnical Description, Third Party Advisory
https://github.com/espressif/esp-idfProduct, Third Party Advisory
https://github.com/espressif/esp32-bt-libProduct, Third Party Advisory
https://www.espressif.com/en/products/socs/esp32Product, Vendor Advisory
https://dl.packetstormsecurity.net/papers/general/braktooth.pdfTechnical Description, Third Party Advisory
https://github.com/espressif/esp-idfProduct, Third Party Advisory
https://github.com/espressif/esp32-bt-libProduct, Third Party Advisory
https://www.espressif.com/en/products/socs/esp32Product, Vendor Advisory

Timeline

Published: Sep 7, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-28136?

How severe is CVE-2021-28136?

CVE-2021-28136 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.81% probability of exploitation in the next 30 days.

How do I fix CVE-2021-28136?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-28136?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST