What is CVE-2025-27840?

CVE-2025-27840 is a medium-severity vulnerability in Espressif Esp32, classified under Hidden Functionality. CVSS score: 6.8/10. Published 2025-03-08.

How severe is CVE-2025-27840?

Medium severity. CVSS v3 base score is 6.8 out of 10.

Is CVE-2025-27840 known to be exploited?

21 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Espressif Esp32

CVE-2025-27840

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

Published 2025-03-08 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:P/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:L.

EPSS exploit prediction

EPSS: 0.013 (69.8th percentile), scored 2026-09-25.

Low probability of exploitation in the next 30 days, but still tracked. 70th percentile — 69.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: -0.000

Affected products

Espressif Esp32 — versions 2025-03-06
Espressif Esp32 Firmware

Weakness classification (CWE)

CWE-912 — Hidden Functionality

Public proof-of-concept exploits

References

github.com/TarlogicSecurity/Talks/blob/main/2025_RootedCon_BluetoothTools.pdf (Third Party Advisory)
x.com/pascal_gujer/status/1898442439704158276 (Third Party Advisory)
www.tarlogic.com/news/backdoor-esp32-chip-infect-ot-devices/ (Third Party Advisory)
www.bleepingcomputer.com/news/security/undocumented-backdoor-found-in-bluetooth… (Exploit, Press/Media Coverage)
reg.rootedcon.com/cfp/schedule/talk/5 (Third Party Advisory)
flyingpenguin.com/ (Technical Description, Third Party Advisory)
github.com/em0gi/CVE-2025-27840 (Product)
github.com/orgs/espruino/discussions/7699 (Issue Tracking)
www.bleepingcomputer.com/news/security/undocumented-commands-found-in-bluetooth… (Exploit, Press/Media Coverage)
darkmentor.com/blog/esp32_non-backdoor/ (Technical Description, Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2025-27840?: CVE-2025-27840 is a medium-severity vulnerability in Espressif Esp32, classified under Hidden Functionality. CVSS score: 6.8/10. Published 2025-03-08.
How severe is CVE-2025-27840?: Medium severity. CVSS v3 base score is 6.8 out of 10.
Is CVE-2025-27840 known to be exploited?: 21 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.