U.Today - The ESP32 chip, which is frequently found in less expensive Bitcoin hardware wallets, has a recently discovered critical vulnerability. The random number generator on the chip has an insufficient entropy problem, which is currently listed under CVE-2025-27840. This defect severely impairs the chip’s capacity to produce secure private keys, putting users at risk of malicious firmware updates or brute-force key-pair attacks that might result in illegal Bitcoin transactions.

Established by Espressif Systems, the ESP32 chip is a well-liked low-power microcontroller that has Bluetooth and Wi-Fi built in. Because of its affordability and versatility, it is a popular choice for lightweight devices like Blockstream’s Jade wallet and do-it-yourself hardware wallet projects. The chip’s affordability and ease of integration make it a popular choice for open-source or experimental wallet designs.

But the ESP32 lacks a hardware security module (HSM), in contrast to more durable and security-focused chips found in popular wallets like Ledger, Trezor or Coldcard. Devices like Ledger rely on secure components that are made especially to generate entropy in a way that is impervious to physical manipulation and reverse engineering as well as to safely store cryptographic secrets.

Due to this design decision, these wallets are less vulnerable to the types of flaws that have recently been found in the ESP32. The fundamental problem lies in the chip’s incapacity to reliably produce high-quality randomness, which is necessary for the nondeterministic design of secure private keys. Attackers may theoretically guess or compute private keys if entropy is predictable or insufficient, jeopardizing user funds.

Furthermore, the architecture of the chip may permit unauthorized parties to push module updates, which could result in transaction signing without the user’s permission. The vulnerability is primarly a concern for less expensive open-source alternatives, but it does not currently impact users of high-end wallets. It is advised that developers who use ESP32 to create wallets incorporate external sources of entropy or switch to more secure architectures.

Cryptocurrency owners who depend on ESP32-powered hardware wallets should keep themselves updated and think about temporarily transferring their money to safer devices until updates or redesigns are made.

This article was originally published on U.Today