日本郵政（ゆうID・ゆうゆうポイント）Data breach / unauthorized access incident
- Occurred on
- Unconfirmed
- Announced on
- October 19, 2026
- Severity
- SCompromise of deep personal data or usable credentials.
- Scale
- 249 accounts
- Main impact
- 日本郵政 confirmed unauthorized logins using IDs and passwords leaked externally and announced that member information for 249 accounts may have been viewed; of those, an address book of 83 entries from 1 account may have been illicitly obtained.
- Information involved
- Email addressPhone numberHome addressFull nameDate of birth
- Cause / key point
- The company explains this was impersonation logins using a list of IDs and passwords leaked externally.About Abuse of credentials
- Industry
- Services & other
- Listing / capital
- Listed company東証プライム 6178(日本郵政)
- Last updated
- October 20, 2026
Stock price reaction to the disclosure日本郵政 / 東証プライム 6178
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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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Same industry
- SSリクルート（カーセンサーnet、C-MATCH）2026.10.21 announced・Affected 3,709,551 records
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Attack method classification: Abuse of credentials(Logging in legitimately with leaked or guessed passwords)
Read the Abuse of credentials guide and national trends →