日本郵便（国際郵便物の調査請求Web受付）Data breach / unauthorized access incident
- Occurred on
- Unconfirmed
- Announced on
- September 25, 2026
- Severity
- BIncidents centered on names and contact details.
- Scale
- 600 records
- Main impact
- Approximately 600 registration records were potentially viewable by a third party due to unauthorized access to the web submission for international mail investigation requests; actual viewing or misuse has not been confirmed. Spam was also sent from a service email account.
- Information involved
- Email addressUser / member IDPhone numberHome addressFull name
- Cause / key point
- The cause is under investigation.
- Industry
- Transport & travel
- Listing / capital
- UnlistedParent company: 日本郵政(東証プライム 6178)
日本郵便 is a subsidiary of 日本郵政.
- Last updated
- October 20, 2026
Stock price reaction to the disclosure日本郵政・親会社 / 東証プライム 6178
Stock information is reference data based on Yahoo Finance and may be delayed. This site does not solicit or advise investment and does not guarantee the accuracy or completeness of this information. We accept no liability for any investment decision based on it.
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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: Unauthorized access (method undisclosed)(Breached, but the technique was not identified or disclosed)
Read the Unauthorized access (method undisclosed) guide and national trends →