New Bluetooth Speaker Bug Lets Hackers Listen to You

Published on: April 19, 2025
Category: Cybersecurity, IoT, Tech Alerts

Introduction

Imagine relaxing at home with your Bluetooth speaker playing music—unaware that a hacker might be silently listening. Shocking? Yes. Possible? Also yes. A newly discovered vulnerability in Bluetooth-enabled speakers, especially those using ESP32 chips, can allow hackers to exploit hidden commands and remotely eavesdrop on users.

What’s the Buzz? Hidden Bugs in Bluetooth Chips

Researchers recently uncovered a medium-severity flaw identified as CVE-2025-27840 in Bluetooth chips manufactured by Espressif (ESP32). These chips are widely used in budget Bluetooth speakers, smart devices, and IoT gadgets.

• Attackers can exploit undocumented HCI commands like 0xFC02 to write into device memory.
• This can give them control over audio streaming or enable persistent eavesdropping modes.

Other Bluetooth Bugs That Make Things Worse

The speaker bug doesn’t exist in isolation. Here are other critical flaws making eavesdropping easier:

1. BlueBorne Vulnerabilities

• Affecting over 5 billion Bluetooth devices
• Allows hackers to take over devices remotely and redirect audio or inject malware

2. Bluetooth Low Energy (BLE) Spoofing

• Using tools like Flipper Zero and BadUSB
• Exploits trust-based Bluetooth pairing to hijack audio channels

3. Firmware Backdoors

• Unpatched devices may allow silent activation of microphones or audio input redirection
• Perfect for espionage or stalking

How Hackers Can Exploit the Bug

1. Hijack Bluetooth communication: Bypass standard authentication and pair silently
2. Manipulate firmware: Using hidden commands to inject malicious code
3. Install persistent backdoors: That record, transmit, or even analyze audio

How to Stay Safe

Here are some essential tips to protect yourself from Bluetooth speaker vulnerabilities:

• Turn off Bluetooth when not in use
• Update speaker firmware via the official manufacturer app or website
• Set devices to non-discoverable mode
• Use a segmented Wi-Fi network to isolate smart devices
• Avoid pairing with unknown devices, especially in public spaces

Conclusion

Hackers don’t always need to break into your phone to steal data—sometimes, they can just listen. With vulnerabilities like CVE-2025-27840 and BlueBorne, your Bluetooth speaker can be turned into a remote spying device if left unpatched or unsecured. Stay alert, stay updated, and always be cautious of what you’re connected to.

Sources & References

• Forbes – ESP32 Hidden Command Warning
• SOC Prime – CVE-2025-27840
• Bitdefender – Zero-day Bluetooth Attacks
• Norton – Smart Speaker Hacking