TLDR
- Bithumb, South Korea’s second-largest crypto exchange, said an outsider broke into its internal employee mobile system and took personal information.
- No crypto funds were reported lost, and Bithumb says the system is separate from its trading platform.
- Daishin Securities said data for 38,490 customers leaked, while Mirae Asset Global Investments said it blocked abnormal access.
- The Financial Supervisory Service said cyberattacks had hit 16 South Korean financial firms as of Oct. 14.
- This is Bithumb’s second internal controls problem this year, after a February error that credited customers with 620,000 BTC.
Bithumb, South Korea’s second-largest crypto exchange by trading volume, said an outsider broke into the internal mobile system its employees use to work and message each other. The exchange said personal information was taken in the breach.
South Korea’s Second-Largest Crypto Exchange Bithumb Confirms Security Breach
According to Yonhap News Agency, South Korea’s second-largest cryptocurrency exchange, Bithumb, confirmed that an unauthorized external party accessed its internal mobile groupware system, resulting in… pic.twitter.com/aMf5l2rVIZ
— Wu Blockchain (@WuBlockchain) October 28, 2026
No cryptocurrency funds were reported lost as of Asian afternoon hours on Wednesday. Bithumb says it is still working out how much was exposed.
What Bithumb Has Said
The exchange found the intrusion on Tuesday. It reported the incident to the Korea Internet & Security Agency and the Personal Information Protection Commission that day, according to Korean media.
Bithumb told Yonhap News Agency it was analyzing the exact scope of the attack. That includes the possibility that member information was involved.
The company also said the breached system runs separately from its trading platform. In its words, “customer virtual assets cannot be accessed through this breach.”
Bithumb has not said whether deposits or withdrawals were affected. It also has not said how many people’s data was exposed.
Yonhap reported that Bithumb planned to make an official announcement Wednesday morning. Cointelegraph said it reached out to the exchange for further comment.
Other Financial Firms Also Hit
Bithumb was one of three financial firms the Financial Supervisory Service said it was assessing on Wednesday. The other two were Daishin Securities and Mirae Asset Global Investments.
Daishin Securities said personal and credit information for 38,490 customers leaked in an outside attack. The firm confirmed the number after the incident.
Mirae Asset Global Investments said it blocked abnormal outside access to some of its web systems. The asset manager said investor information was not affected and that it was investigating.
FSS Governor Lee Chan-jin spoke about the attacks at a meeting with bank holding company chairs. “I understand that major financial investment companies experienced overall hacking incidents yesterday,” he said.
Earlier in the month, Lee said cyberattacks had hit 16 South Korean financial firms as of Oct. 14. The Korea Times also reported on the Mirae and Daishin incidents.
A Second Problem This Year
This is the second time Bithumb’s internal controls have come under scrutiny in 2026. In February, the exchange mistakenly credited customers with 620,000 BTC instead of 620,000 won.
The Bitcoin amount was worth more than $40 billion at the time. CEO Lee Jae-won blamed the error on weak internal controls.
He said the exchange was “acutely aware of the deficiency in internal system control.” Bithumb has not yet said how many people were affected by the latest breach, and regulators are still assessing the three firms.
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