集英社（HAPPY PLUS COMMUNITY）Data breach / unauthorized access incident
- Occurred on
- September 9, 2026
- Announced on
- September 28, 2026
- Severity
- AFinancial and HR records — information that easily translates into monetary damage.
- Scale
- 2,835 people
- Main impact
- Confirmed leakage of the addresses, family status, photos, SNS information, and email contents of 2,835 people. These are personal data and pose risks such as impersonation and privacy infringement.
- Information involved
- Home address
- Cause / key point
- Unauthorized access believed to be an attack targeting API credentials resulting from misconfigured CMS settings.About Abuse of credentials
- Industry
- Media & entertainment
- Listing / capital
- Unlisted
集英社 is unlisted.
- Last updated
- October 20, 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
Related incidents
Browse the database →Incidents sharing the same company, service, attack method or industry (grouped automatically from the disclosures).
Incidents related to "community"
Incidents where the damage spread through the same service or system.
Same attack method
- A日本経済新聞社(日経)2026.10.16 announced・Affected 1,830,000 records
- Sチャーム本店2026.09.01 announced・Affected 370,000 records
- ACAMPFIRE2026.06.02 announced・Affected 225,846 accounts
- Aウエーブ（Webアップロード）2026.04.01 announced・Affected 176,810 records
- Aシチズン時計（問い合わせ管理）2026.10.06 announced・Affected 100,000 people
- Bイノベーション（GitHub）2026.08.07 announced・Affected 62,689 people
Same industry
- Sクリプトン（SONICWIRE・D2R）2026.10.19 announced・Affected 420,000 records
- SNTTソルマーレ（コミックシーモア）2026.10.15 announced・Affected Unknown
- S日本経済新聞社2026.10.04 announced・Affected 1,646 people
- SCINRA, Inc.2026.08.27 announced・Affected 21,508 people
- Sユニバーサル ミュージック2026.05.18 announced・Affected 3,100,000 records
- Sメディカ出版2026.05.13 announced・Affected 641,000 people
Attack method classification: Abuse of credentials(Logging in legitimately with leaked or guessed passwords)
Read the Abuse of credentials guide and national trends →