CZ Warns of 4 Data Leaks in One Day: Coinbase, Bithumb, and More

A single data leak can give scammers enough information to make their next attack look convincing. On October 28, 2026, Binance co-founder Changpeng Zhao, widely known as CZ Binance, highlighted four financial-sector security incidents involving Coinbase, Bithumb, Mirae Asset Global Investments, and Daishin Securities.

The incidents were not identical. Coinbase said a security incident at its third-party analytics provider, Amplitude, exposed contact data belonging to a small subset of customers, while customer funds remained unaffected. In South Korea, Bithumb reported unauthorized access to an internal system, and investigations into the scope of the incident were ongoing. Mirae Asset also reported unauthorized access to certain systems, although a customer data leak had not been confirmed at the time of reporting. Daishin Securities, meanwhile, disclosed that personal information belonging to 38,490 customers had been exposed.

The CZ data leak warning highlights a risk that extends beyond the original incident: stolen information can help criminals target crypto users with phishing messages, impersonation attempts, and SIM swapping. Although users cannot control every company's security practices, practical precautions can make their accounts harder to compromise.

Key Takeaways

• Four reported security incidents involved Coinbase's vendor, Bithumb, Mirae Asset, and Daishin Securities, but the confirmed impact differed across organizations.

• A crypto data breach can create follow-up risks, including phishing, social engineering, and SIM swapping, even when exchange funds are not affected.

• Unique passwords, phishing-resistant authentication, limited personal information, and withdrawal safeguards can reduce account takeover risks.

What Happened in the Four Data Security Incidents?

The incidents drew attention because they affected both crypto-related services and traditional financial firms.

Coinbase and Amplitude

Coinbase said an incident involving analytics provider Amplitude exposed some customer contact information. Coinbase stated that it found no evidence of unauthorized access to its own systems and that customer funds were not affected. The incident illustrates how third-party vendors can create security risks even when an exchange's core systems have not been breached.

Bithumb

The South Korean crypto exchange reported unauthorized access to its internal mobile groupware system. Investigations were needed to establish the full scope of the incident and whether additional customer information was affected. A Bithumb data breach should therefore be understood in the context of what investigators have confirmed, rather than assumptions about every category of customer data.

Mirae Asset Global Investments

The firm reported unauthorized access involving certain online systems. At the time of reporting, the investigation had not confirmed that customer personal information had been leaked.

Daishin Securities

The brokerage disclosed that personal information belonging to 38,490 customers had been exposed, including names, email addresses, and mobile phone numbers. Reports also described exposure of additional personal and financial information.

These cases are not proof that all four companies suffered the same type or scale of customer data loss. However, they demonstrate why companies and customers need to take data security seriously.

Why Crypto Exchange Data Leaks Can Be Dangerous

A crypto exchange data leak does not automatically mean an attacker can access a user's account or withdraw funds. The risk is that leaked information can make a scam more believable.

Criminals may use names, email addresses, phone numbers, or other exposed details to impersonate exchange support teams. A message that references a real security incident can pressure users into clicking a malicious link, sharing a verification code, or transferring assets to a wallet controlled by a scammer.

Three common threats deserve attention:

• Crypto phishing scams: Fake emails, websites, and messages imitate exchanges and ask users to reveal login credentials or authentication codes.

• SIM swapping crypto attacks: Criminals try to convince a mobile carrier to transfer a victim's phone number to another SIM, potentially intercepting SMS verification codes.

• Social engineering: Scammers use personal information to sound credible, create urgency, and manipulate users into bypassing their own security precautions.

In more serious cases, leaked home addresses combined with publicly disclosed crypto holdings can expose individuals to physical extortion or robbery. Avoid sharing unnecessary personal details or publicizing the size of your holdings.

Crypto Security Tips: How to Protect Your Accounts

You cannot prevent every company from experiencing a breach, but you can reduce how much information is exposed and make account takeover more difficult.

1. Reduce the Personal Information You Share

Use a unique email address or alias for each exchange where practical. Email alias services can help separate accounts and make it easier to identify where unwanted messages originate. Provide only the personal information required for verification, and avoid filling in optional profile fields unnecessarily.

Where permitted and practical, consider using a dedicated phone number for financial accounts. Ask your mobile carrier whether it supports a port-out PIN or number lock to make unauthorized number transfers harder.

2. Strengthen Account Authentication

Use a long, unique password generated and stored in a reputable password manager. Never reuse an exchange password for your email or other services.

Enable a passkey or hardware security key where supported. An authenticator app is another option and is generally preferable to SMS-based two-factor authentication because it does not rely on your mobile number. Keep recovery codes in a secure location separate from your device.

You should also enable an anti-phishing code if your exchange offers one. This helps you check whether a message contains the code associated with legitimate communications from that platform.

3. Limit What an Attacker Can Do

Review your exchange's security settings and enable withdrawal address whitelisting or withdrawal time locks if available. Check active sessions and revoke access from devices you do not recognize.

If you use API keys for trading, delete unused keys and restrict necessary keys to specific IP addresses where possible. Disable withdrawal permissions unless they are genuinely required.

4. Treat Unexpected Messages as Suspicious

After a breach announcement, scammers may send fake security alerts, account recovery offers, or messages claiming to help recover lost funds. They may even know your name or details about your trading activity.

Do not click links in unexpected emails or text messages. Open the exchange's official app or type its website address yourself. Legitimate support staff should never ask you to disclose your password, two-factor authentication codes, or wallet seed phrase.

What Should You Do After a Data Breach?

If an exchange or service you use announces a breach, take these steps promptly:

1. Change the affected password and update any other account where you reused it.

2. Check your email address on Have I Been Pwned to see whether it appears in known data breaches.

3. Review active sessions and revoke suspicious access. Remove API keys you no longer use.

4. Check recent withdrawals, login activity, recovery settings, and authentication methods.

5. Be especially cautious of emails, calls, and texts referencing the incident. Verify any notification through the service's official website or app.

If you notice an unauthorized withdrawal or account change, contact the exchange through its official support channel immediately. Do not pay anyone who promises guaranteed recovery of stolen cryptocurrency.

Conclusion

The Coinbase Bithumb data leak discussion and the wider incidents involving Korean financial firms show why data security matters across the financial industry. The precise impact of each incident differs, but leaked information can give scammers an opportunity to target users through phishing, SIM swapping, and impersonation.

The best response is to prepare before an incident occurs: minimize shared personal information, use stronger authentication, secure your phone number, and review account permissions regularly. If you trade crypto, make account security part of your routine rather than waiting for a breach announcement.

Ready to explore crypto markets? Register on Bitrue and make time to review your account security settings before trading.

FAQ

What did CZ Binance warn about?

CZ highlighted four reported security incidents involving Coinbase, Bithumb, Mirae Asset, and Daishin Securities.

Was Coinbase directly hacked?

Coinbase said the incident originated at analytics provider Amplitude and that its own systems showed no evidence of unauthorized access.

What is a Bithumb data leak?

Bithumb reported unauthorized access to an internal system. The full scope of affected information was still under investigation in initial reports.

How can I avoid SIM swapping crypto attacks?

Use stronger authentication than SMS where possible, and ask your mobile carrier about a port-out PIN or number lock.

What should I do after a crypto data breach?

Change affected or reused passwords, revoke suspicious sessions and API keys, review withdrawals, and watch for phishing attempts.

Disclaimer: The views expressed belong exclusively to the author and do not reflect the views of this platform. This platform and its affiliates disclaim any responsibility for the accuracy or suitability of the information provided. It is for informational purposes only and not intended as financial or investment advice.