和歌山県立21校（ライデン・スクール）Data breach / unauthorized access incident
- Occurred on
- Unconfirmed
- Announced on
- October 15, 2026
- Severity
- BIncidents centered on names and contact details.
- Scale
- 10,006 people
- Main impact
- Due to unauthorized access to アルカディア, personal data for approximately 約1万6千 registrants of contact emails for 県立21校 — including names, email addresses, current school names, grade levels, etc. — may have been leaked.
- Information involved
- Email addressFull name
- Cause / key point
- The cause is under investigation.
- Industry
- Government & municipal
- Listing / capital
- Government / public body
- Last updated
- October 20, 2026
Is this incident worth paying attention to?
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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.
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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Other incidents at 和歌山県立21校
Incidents related to "アルカディア"
Incidents where the damage spread through the same service or system.
- B栃木県警（アルカディア利用内部システム）2026.10.20 announced・Affected 3,900 people
- B埼玉県警（アルカディア安否確認システム）2026.10.18 announced・Affected 13,000 people
- B伊万里・有田消防本部（NET119緊急通報システム）2026.10.15 announced・Affected 15 people
- A一宮市（アルカディア提供のメール配信・Net119等）2026.10.14 announced・Affected Unknown
- A斑鳩町（防災情報メール・ハザードン）2026.10.13 announced・Affected Unknown
- A箕面市（防災情報配信サービス）2026.10.13 announced・Affected Unknown
Same attack method
- SSソースネクスト2026.10.15 announced・Affected 22,519,960 records
- SSバーガーキング・ジャパン(公式アプリ)2026.10.15 announced・Affected 11,180,000 records
- SS焼肉きんぐ2026.10.05 announced・Affected 10,788,963 records
- Bユミルリンク（メール配信システム）2026.10.19 announced・Affected 9,000,000 records
- SSタイムズカー(タイムズモビリティ)2026.09.25 announced・Affected 6,600,000 accounts
- Sブックオフグループ(ブックオフコーポレーション)2026.10.09 announced・Affected 6,383,279 people
Same industry
- S市立岸和田市民病院（患者書類）2026.10.16 announced・Affected 1 people
- S大崎地域広域行政事務組合消防本部（NET119・119RAIDEN）2026.10.14 announced・Affected 45 people
- S神奈川県警（使用済み運転免許証）2026.10.09 announced・Affected 30 records
- S長崎市（マイナンバーカード特急発行書類の紛失）2026.09.08 announced・Affected 4 people
- S村田製作所2026.04.27 announced・Affected 73,000 records
- S静岡市2026.01.30 announced・Affected 3,950 people
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 →