楽天ブックスネットワークData breach / unauthorized access incident
- Occurred on
- Unconfirmed
- Announced on
- August 21, 2026
- Severity
- BIncidents centered on names and contact details.
- Scale
- 33,000 records
- Main impact
- Approximately 33,000 delivery addresses etc. are reported to be at risk of disclosure; financial information is not included and an actual leak has not been confirmed.
- Information involved
- Not specified in the disclosure
- Cause / key point
- Cause is under investigation.
- Industry
- IT & telecom
- Listing / capital
- UnlistedParent company.: 楽天グループ(東証プライム 4755)
楽天ブックスネットワーク is a subsidiary of 楽天グループ.
- Sources
- Last updated
- October 20, 2026
Stock price reaction to the disclosure楽天グループ・親会社 / 東証プライム 4755
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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: Under investigation / not stated(Cause not disclosed)
Read the Under investigation / not stated guide and national trends →