Coinbase tells customers most crypto in its custody is offline, citing controls after the Binance hack

Coinbase has told customers that the vast majority of the crypto held under its custody is kept offline and separated from systems that could be targeted by hackers, framing the disclosure as a response to concerns raised by a major industry breach.

The update comes against the backdrop of the $6.4 billion hack reported in connection with Binance, which has renewed scrutiny of how exchanges and custody providers safeguard customer assets. Coinbase said it was not affected by that specific incident, and used the occasion to describe the security architecture behind its custody operations.

At the core of Coinbase’s message is the company’s claim that offline storage, often referred to as “cold storage,” covers over 99% of customer assets. Cold storage generally means private keys used to authorize blockchain transactions are not continuously connected to the internet, reducing the likelihood that remote attackers can directly move funds.

Coinbase also described key-management controls meant to limit the impact of a compromise. The company said it uses a setup that splits private keys, so no single component holding a complete key is available in the way attackers could exploit if keys were kept in one place.

In addition, Coinbase said it employs “kill switches,” mechanisms intended to rapidly halt access or functionality if suspicious activity is detected or if a security incident requires emergency containment. The combination of offline storage, split key controls, and kill switches is presented as a layered defense intended to prevent unauthorized transfers even under adverse scenarios.