# CVE-2025-27840: Security feature bypass in ESP32

> Hidden HCI commands in Espressif ESP32 chips allow attackers to write memory, potentially enabling code execution or privilege escalation.

- **Severity:** Medium 6.8 (`CVSS:3.1/AV:P/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Mar 2025
- **Updated:** 12 May 2025
- **Also known as:** GHSA-jfwf-rfmg-7f8m

## What is CVE-2025-27840?

CVE-2025-27840 is a medium-severity vulnerability in Espressif ESP32, published on 8 Mar 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

Weakness: CWE-912 (Hidden Functionality)

## Which versions are affected by CVE-2025-27840?

It affects 1 product.


Products: Espressif Esp32 Firmware.

## How do I fix CVE-2025-27840?

No fix has been published for CVE-2025-27840 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-27840 being exploited?

There is no known exploitation of CVE-2025-27840 in the wild and no public exploit code.

Public exploit code:

- Bitcoin Cryptanalysis: CVE-2025-27840 Vulnerability in ESP32 Microcontrollers Puts Billions of IoT Devices at Risk via Wi-Fi & Bluetooth (github_poc): https://github.com/demining/Bluetooth-Attacks-CVE-2025-27840
- Expanded version of the code shown at RootedCON redone in python - CVE-2025-27840 (github_poc): https://github.com/em0gi/CVE-2025-27840
- A Work-In-Progress for CVE-2025-27840  (github_poc): https://github.com/v3ilsm1th/CVE-2025-27840-WIP
- Firmware for getting a power trace of the behavior of the bluetooth module on the ESP32 when the ESP32 is sent the undocumented hci bluetooth commands (CVE-2025-27840). Uses ESP-IDF v5.0.8 and v5.0.9. (github_poc): https://github.com/JasonW88/esp32-cve-2025-27840-power-trace-experiment

## Other vulnerabilities in Espressif ESP32

- [CVE-2021-34173](https://insights.sbomify.com/CVE-2021-34173/): Denial of service in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-27840 and fix it if it is affected.

What it is: CVE-2025-27840 is a medium-severity vulnerability in Espressif ESP32, published on 8 Mar 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-27840 in the wild and no public exploit code.

Affected product: Espressif ESP32. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-27840/ (Markdown: https://insights.sbomify.com/CVE-2025-27840/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-27840
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-27840
- OSV: https://osv.dev/vulnerability/CVE-2025-27840

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-27840/
Summaries are generated and may contain mistakes; the official description above is the record.