NTT Docomo says data on up to about 295,000 customer accounts leaked from its My docomo site
November 4, 2026 (November 4, 2026)
Japan's largest mobile carrier, NTT Docomo, said unauthorized access to its My docomo customer site on November 4 may have leaked information on up to 294,839 accounts: 204,157 individual and 90,682 corporate. Alerts flagged a large volume of access and Docomo put the site into maintenance. It blocked the route the attackers used and brought the service back, but saw signs of access again, took it offline a second time and confirmed the leak. For all affected users the data includes name, date of birth, address, phone number, email, the number of an identity document and contract details such as the phone number and rate plan. For some it also includes bank account details, information on legal representatives and company details. Docomo began sending SMS notices on November 6 and plans a consolation payment. It has not said how the attackers got in.
Why it matters
Names, addresses, contract details and ID numbers are what scammers need to pose convincingly as the carrier or as the customer.
What defenders can take from it
- Docomo customers: treat calls, SMS and email that mention your contract or ID with suspicion, and do not give passwords, PINs or card numbers.
- Check your account for logins, purchases or contract changes you did not make, and contact Docomo through its official channels.
- Companies: watch customer portals for unusual volumes of account lookups, which can signal a scraping attack.