CVE-2025-27840

Name: CVE-2025-27840
Creator: NVD / NIST
Published: 2025-03-08T20:15:36.027+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.8/10EPSS 1.26%

Last modified Jun 17, 2026

CVE-2025-27840 is a medium-severity vulnerability rated 6.8/10 on the CVSS scale. Espressif ESP32 chips allow 29 hidden HCI commands, such as 0xFC02 (Write memory).. EPSS estimates a 1.26% chance of exploitation in the next 30 days.

Description

Espressif ESP32 chips allow 29 hidden HCI commands, such as 0xFC02 (Write memory).

Metrics

CVSS 3.1

6.8/10

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

EPSS Probability

1.26%

65.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-912

Affected Software

Vendor	Product	Versions
Espressif	Esp32 Firmware	All versions

References

https://cheriot.org/auditing/backdoor/2025/03/09/no-esp32-style-backdoor.htmlTechnical Description, Third Party Advisory
https://darkmentor.com/blog/esp32_non-backdoor/Exploit, Technical Description, Third Party Advisory
https://flyingpenguin.com/?p=67838Technical Description, Third Party Advisory
https://github.com/TarlogicSecurity/Talks/blob/main/2025_RootedCon_BluetoothTools.pdfThird Party Advisory
https://github.com/em0gi/CVE-2025-27840Product
https://github.com/esphome/esphome/discussions/8382Issue Tracking
https://github.com/orgs/espruino/discussions/7699Issue Tracking
https://news.ycombinator.com/item?id=43301369Issue Tracking
https://news.ycombinator.com/item?id=43308740Issue Tracking
https://reg.rootedcon.com/cfp/schedule/talk/5Third Party Advisory
https://www.bleepingcomputer.com/news/security/undocumented-backdoor-found-in-bluetooth-chip-used-by-a-billion-devices/Exploit, Press/Media Coverage
https://www.bleepingcomputer.com/news/security/undocumented-commands-found-in-bluetooth-chip-used-by-a-billion-devices/Exploit, Press/Media Coverage
https://www.espressif.com/en/news/Response_ESP32_BluetoothPress/Media Coverage
https://www.tarlogic.com/news/backdoor-esp32-chip-infect-ot-devices/Third Party Advisory
https://x.com/pascal_gujer/status/1898442439704158276Third Party Advisory

Timeline

Published: Mar 8, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2025-27840?

Espressif ESP32 chips allow 29 hidden HCI commands, such as 0xFC02 (Write memory).

How severe is CVE-2025-27840?

CVE-2025-27840 has a CVSS score of 6.8/10 (MEDIUM severity). The EPSS model estimates a 1.26% probability of exploitation in the next 30 days.

How do I fix CVE-2025-27840?

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-2025-27840?

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

Scan your code now

Source: NVD / NIST