Coinbase and Bithumb customers exposed by separate data leaks

Customers of Coinbase and Bithumb had their information exposed following attacks on the South Korean exchange and the analytics firm used by Coinbase.

An undisclosed number of Bithumb users had personal details leaked after an “external party” reportedly broke into the exchange’s internal mobile groupware systems.

Amplitude, the third-party analytics vendor Coinbase relies on, meanwhile experienced a security incident that leaked customer contact data.

Coinbase insists the fault lay outside the exchange

Since the news emerged, Coinbase has been managing the fallout and telling customers that its own platform was not breached.

It described the impact as limited to a “small subset” of customers and said it had found “no evidence of unauthorized access to Coinbase systems, and customer funds were not impacted.”

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

Breaches touched three further finance-sector firms

South Korean traditional finance houses Mirae Asset Global Investments and Daishin Securities also experienced a data breach yesterday.

The credit card and personal details of nearly 38,500 Daishin Securities clients were leaked, while Mirae’s customer information reportedly showed no signs of being exposed in the incident.

The situation in South Korea was serious enough that the presidential office convened an emergency meeting to address the breaches.

Wagyu, a company that offers Monero swaps, has reportedly also been hit by a data breach.

??????? lol these guys are so funny

— Tay (@tayvano_) October 28, 2026

Ransomware outfit WhiteArmor leaked three months of customer data, including transaction amounts and times, IP addresses and countries of origin.

Wagyu is said to have turned down the $5 million ransom demand. WhiteArmor is also reported to be holding Chinese electronics business Hisense and gambling firm Gamdom to ransoms of $5 million and $15 million in BTC, respectively.

Earlier leaks also hit Coinbase and Bithumb

In 2024, cybercriminals hired members of Coinbase’s customer support team to make off with user data, resulting in a major breach.

Roughly 70,000 customers had their data affected, and the company turned down a $20 million BTC ransom request.

A separate incident followed in December 2025, when a Coinbase contractor accessed the data of around 30 users.

In 2021, the data of 6,000 Coinbase users also appears to have leaked, which set off a social engineering campaign aimed at taking over accounts and stealing crypto.

Bithumb, meanwhile, had 31,000 users’ data leaked in 2017, leading to the theft of 5.9 million worth of crypto.