Bithumb Discloses Internal Data Breach, Says Customer Assets Unaffected

South Korean cryptocurrency exchange Bithumb disclosed a breach of its internal employee mobile system on Tuesday and notified two national regulators the same day, Yonhap News Agency reported Wednesday.

Bithumb discovered the compromise of its in-house mobile platform — the system staff use to communicate and share information internally — and alerted the Korea Internet & Security Agency (KISA) and the Personal Information Protection Commission, according to Yonhap, which cited industry sources. The exchange is now investigating the full scope of the incident, including whether member data was exposed.

What does Bithumb say was compromised?

In a statement to Yonhap, Bithumb confirmed the investigation remains ongoing. "We are analyzing the exact scope, including the possibility of member information being involved," the exchange said. "We will provide an official announcement this morning."

The company drew a firm operational boundary around the damage. "The internal work system is separated from the virtual asset trading system, so customer virtual assets cannot be accessed through this breach," Bithumb said.

That separation matters for Bithumb's business position. The exchange has set a 2028 timetable for an initial public offering and is overhauling its internal controls ahead of that listing. Any confirmed leak of member personal data would land in the middle of that cleanup and could draw scrutiny from the Personal Information Protection Commission, the agency that enforces South Korea's data protection law.

How bad is the wider attack wave?

The Bithumb incident is one entry in a broader campaign against South Korean financial institutions. Governor Lee Chan-jin told a meeting at the Financial Supervisory Authority headquarters on Wednesday that cyberattacks had hit 16 South Korean financial firms as of Oct. 14.

Two of those victims have already quantified or scoped their exposure:

• Daishin Securities disclosed that personal and credit information belonging to 38,490 customers was leaked.
• Mirae Asset Global Investments reported that it blocked abnormal external access to some of its web systems and opened an investigation. The company said, per Yonhap, that investor information was not affected.

For comparison, the Daishin figure — 38,490 customer records covering both personal and credit data — gives a sense of the scale at stake if Bithumb's probe confirms member information was involved. Bithumb has not yet disclosed any equivalent count.

What happens next?

Bithumb said it would issue an official announcement, and the scope of any member-data exposure remains the central open question. The exchange must also report findings to KISA and the Personal Information Protection Commission, both of which can investigate independently under their respective mandates.

The episode tests whether Bithumb's claimed network segmentation between internal systems and the trading platform holds under regulatory review — a question the FSS, which has been tracking the 16-firm attack wave, is likely to press as South Korea's financial-sector cybersecurity window tightens.