What’s Vulnerable › Vulnerabilities

CVE-2025-27840

• Severity: medium (CVSS 6.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-03-08 · updated 2026-06-17
• Weakness: CWE-912

Description

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

Affected products

• Espressif ESP32: all versions

References

• https://cheriot.org/auditing/backdoor/2025/03/09/no-esp32-style-backdoor.html
• https://darkmentor.com/blog/esp32_non-backdoor/
• https://flyingpenguin.com/?p=67838
• https://github.com/TarlogicSecurity/Talks/blob/main/2025_RootedCon_BluetoothTools.pdf
• https://github.com/em0gi/CVE-2025-27840
• https://github.com/esphome/esphome/discussions/8382
• https://github.com/orgs/espruino/discussions/7699
• https://news.ycombinator.com/item?id=43301369
• https://news.ycombinator.com/item?id=43308740
• https://reg.rootedcon.com/cfp/schedule/talk/5
• https://www.bleepingcomputer.com/news/security/undocumented-backdoor-found-in-bluetooth-chip-used-by-a-billion-devices/
• https://www.bleepingcomputer.com/news/security/undocumented-commands-found-in-bluetooth-chip-used-by-a-billion-devices/

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