Vulnerability Found in WabiSabi CoinJoin Protocol

The team behind Ginger Wallet, a privacy-focused fork of Wasabi Wallet, has addressed a vulnerability in the WabiSabi CoinJoin protocol that allowed for the deanonymization of users.

The bug, discovered by a programmer known as drkgry, affects Wasabi Wallet version 2.2.1.0, Ginger Wallet 2.0.13, the BTCPay Server plugin 1.0.101.0, and earlier releases.

CoinJoin technology enables multiple users to combine their inputs and outputs into a single transaction. This mixing of coins prevents the identification of its participants.

The WabiSabi protocol coordinates this process, allowing clients to contribute varying amounts in a single round. All information is concealed during the registration of outputs through the use of anonymous accounts.

WabiSabi users generate private accounts, among other things, using key parameters and a maximum amount. The vulnerability allowed a malicious coordinator to assign their own unique values to these criteria.

This opened the possibility for tracking users throughout the coin mixing process, enabling the correlation of inputs and outputs, wallet clustering, and data deanonymization.

In May, zkSNACKs, the developer of Wasabi Wallet, decided to cease the CoinJoin service to comply with US regulatory requirements.