Coinbase Vendor Breach Exposes Customer Contact Data

Coinbase revealed that contact information for some of its clients was exposed during a security incident at analytics vendor Amplitude. The cryptocurrency exchange stated its own platforms were not breached and that customer assets remain secure.

The announcement came one day before Coinbase is scheduled to release its third-quarter earnings report. Additionally, South Korea-based Bithump confirmed that one of its internal staff systems was compromised.

Coinbase Mentions "Small Subset" Without Providing a Specific Figure

Coinbase posted its version of events on its X support account.

Coinbase has not had a data breach.

Amplitude, an analytics vendor, experienced a security incident which impacted a small subset of Coinbase customer contact data, among other Amplitude customers.

We've found no evidence of unauthorized access to Coinbase systems, and...

— Coinbase Support (@CoinbaseSupport) October 28, 2026

The posting did not disclose which specific contact fields were exposed. An anonymous X account alleged that attackers obtained information for more than 70,000 users. SlowMist Chief Information Security Officer 23pds shared that claim.

Coinbase has yet to confirm any specific number. BeInCrypto has contacted Coinbase for a response.

This is not the first time Coinbase has dealt with attempts to weaponize client data. In May 2025, the exchange stated that criminals bribed overseas support contractors to obtain customer records for impersonation scams.

The new disclosure comes right before Coinbase's next financial report. The exchange will release its third-quarter results after markets close on Thursday. Analysts project revenue of roughly $1.2 billion.

Since the incident occurred after the quarter ended on September 30, any associated costs would more likely appear in the fourth-quarter results. However, a cost estimate in Thursday's update could indicate whether the incident will affect Coinbase's finances.

Bithumb States the Breach Was Contained to Its Staff System

Coinbase is not the only exchange dealing with a leak this week. In South Korea, Bithumb stated that an unauthorized external party accessed the mobile groupware system used by its employees internally.

The exchange reported the incident to the Korea Internet & Security Agency (KISA).

"So far it appears to be focused on internal employee information, but we are analyzing the details while leaving open the possibility that member information was included," a Bithumb official said.

Bithumb added that its work system is separate from its trading platform. Therefore, it said customer crypto assets cannot be accessed through this breach.

Bithumb's past shows how leaked contact details can lead to financial losses. In 2017, a database stolen from an employee's computer exposed phone numbers and emails for about 3% of customers. Bithumb later linked wallet thefts to phishing attacks.