ニフティ（回線申込・受付管理システム）Data breach / unauthorized access incident
- Occurred on
- October 19, 2026
- Announced on
- October 19, 2026
- Severity
- AFinancial and HR records — information that easily translates into monetary damage.
- Scale
- 542,513 records
- Main impact
- It was disclosed that up to 542,513 personal information records may have been leaked due to unauthorized access to the line application/acceptance management system, potentially affecting users who applied for optical lines outside the company's website since 2019. The data is said to include names, addresses, member IDs, phone numbers, and email addresses, and it is stated that the system does not hold bank account or credit card information; the actual scope of the leak is under investigation.
- Information involved
- Email addressUser / member IDPhone numberHome addressFull nameDate of birth
- Cause / key point
- Intrusion via unauthorized external access to the line application/acceptance management system (details are currently under investigation).
- Industry
- IT & telecom
- Last updated
- October 22, 2026
Is this incident worth paying attention to?
Written & reviewed
Reviewed byYutaro SasaoFounder & CEO, MediaLeap Inc.
CEO of MediaLeap Inc. Working on both sides of web advertising and web media since 2013; founded the company in May 2025.
Review scope: cross-checking against primary sources (official and government announcements), verifying claims stay within the facts, and checking source attribution。Last reviewed:
Written by:Leak Watch editorial team (AI-assisted drafts verified against sources by the editorial team) · Reviewer profile · Request a correction
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Attack method classification: Unauthorized access (method undisclosed)(Breached, but the technique was not identified or disclosed)
Read the Unauthorized access (method undisclosed) guide and national trends →