Three South Korean financial firms reported data breaches on Wednesday 28 October 2026, according to the Yonhap news agency, in the latest sign of a hacking wave sweeping the country's financial sector. Crypto exchange Bithumb, brokerage Daishin Securities and asset manager Mirae Asset Global Investments all confirmed incidents, with regulators now assessing the damage.

Bithumb said its in-house mobile system had been hacked and personal information leaked, and that it was investigating whether member data was included. Bithumb said its exchange systems are separate from the hacked system, so customer assets were unaffected, though the data scope is still being investigated. Daishin Securities said about 38,000 pieces of customer information had been leaked and that it had taken emergency measures.

What Daishin found

Daishin said it first detected signs of unauthorised access on 17 October to a server supporting remote securities-account opening, and confirmed the information leak on 26 October after a ten-day investigation with the Financial Security Institute. According to Aju Press, about 60,000 requests disguised as legitimate service traffic were reviewed, and eight categories of information were exposed, including customer names, email and postal addresses, bank names and account numbers, securities account numbers and mobile phone numbers. Mirae Asset Global Investments also confirmed a hacking incident, with authorities assessing the situation.

A wider wave

The three cases follow a wave of hacking attacks at 16 South Korean financial firms, including banks, causing around 100,000 cases of data leaks so far this month, according to the Financial Services Commission earlier in October. Seoul's Science Ministry has also urged website operators to check for PHP flaws that let attackers run commands without logging in. Customers of the affected firms should watch for phishing messages using their leaked details.