CVE-2025-27840
CVE-2025-27840 is a medium-severity vulnerability in Espressif Esp32 Firmware with a CVSS 3.x base score of 6.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-912.
Key facts
- Severity: Medium (CVSS 3.x base score 6.8)
- EPSS exploit prediction: 1% (66th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-7816
- Weakness: CWE-912
- Affected product: Espressif Esp32 Firmware
- Published:
- Last modified:
Description
Espressif ESP32 chips allow 29 hidden HCI commands, such as 0xFC02 (Write memory).
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 3.x base score of 6.8, rated medium severity. It is exploitable over physical access with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability low.
- Is CVE-2025-27840 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2025-27840?
- CVE-2025-27840 affects Espressif Esp32 Firmware. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2025-27840?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2025-27840 have an EU (EUVD) identifier?
- Yes. CVE-2025-27840 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-7816.
- When was CVE-2025-27840 published?
- CVE-2025-27840 was published on 2025-03-08 and last updated on 2026-06-17.
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/
- https://www.espressif.com/en/news/Response_ESP32_Bluetooth
- https://www.tarlogic.com/news/backdoor-esp32-chip-infect-ot-devices/
- https://x.com/pascal_gujer/status/1898442439704158276
Affected products (1)
- cpe:2.3:o:espressif:esp32_firmware:-:*:*:*:*:*:*:*
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