JR東日本（えきねっと・大人の休日倶楽部）Data breach / unauthorized access incident
- Occurred on
- Unconfirmed
- Announced on
- October 9, 2026
- Severity
- BIncidents centered on names and contact details.
- Scale
- Unknown
- Main impact
- An external email delivery service reported and it was announced that personal information of えきねっと・大人の休日倶楽部会員 was judged not to have been leaked. However, there was business impact such as partial suspension of member email distribution.
- Information involved
- Email address
- Cause / key point
- Unauthorized access that occurred at IDCフロンティア社.
- Industry
- Transport & travel
- Listing / capital
- Listed company東証プライム 9020(東日本旅客鉄道)
- Last updated
- October 20, 2026
Stock price reaction to the disclosure東日本旅客鉄道 / 東証プライム 9020
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CEO of MediaLeap Inc. Working on both sides of web advertising and web media since 2013; founded the company in May 2025.
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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 →