株式会社コバヤシData breach / unauthorized access incident
- Occurred on
- November 4, 2025
- Announced on
- January 21, 2026
- Severity
- SCompromise of deep personal data or usable credentials.
- Scale
- 8,149 records
- Main impact
- 8,149 personal information records held by our company were illegally obtained and published on an external website; these included names, addresses, dates of birth, contact details of applicants, sole proprietors, employees, etc., and sensitive data such as bank account numbers, passport numbers, and Basic Pension Numbers.
- Information involved
- Full nameHome addressDate of birthPhone numberEmail addressUser / member IDIdentity verification data
- Cause / key point
- An unauthorized third party exploited vulnerabilities in part of the system and, via unauthorized access, installed malicious software.About Exploitation of vulnerabilities
- Industry
- Manufacturing
- Listing / capital
- Unlisted
- Sources
- 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 "プログラム"
Incidents where the damage spread through the same service or system.
- Bリンクステーション（GETTIIS会員情報）2026.10.19 announced・Affected Unknown
- SSEストアー(ショップサーブ)2026.10.16 announced・Affected 23,356,000 people
- Aアズマ（hitmart）2026.10.08 announced・Affected Unknown
- A損保ジャパン（SMILING ROAD）2026.10.07 announced・Affected 60,000 records
- Aシチズン時計（問い合わせ管理）2026.10.06 announced・Affected 100,000 people
- Sホワイトエッセンス（予約・基幹システム）2026.10.05 announced・Affected 1,050,000 accounts
Incidents related to "パスポート"
Incidents where the damage spread through the same service or system.
Same attack method
- SSHelpfeel（Gyazo）2026.09.16 announced・Affected 23,620,000 records
- SSSKDDI(ISP事業者向けメール基盤)2026.06.23 announced・Affected 12,231,954 people
- Sムラウチドットコム2026.09.15 announced・Affected 7,710,000 records
- ALEAN BODY2026.09.15 announced・Affected 440,000 accounts
- Aユーザベース（NewsPicks）2026.10.08 announced・Affected 362,000 records
- A加賀ソルネット（アカデミコナビ）2026.08.17 announced・Affected 166,000 people
Same industry
- SS精電舎電子工業2026.07.21 announced・Affected Unknown
- SS富士フイルムメディカル株式会社2025.12.23 announced・Affected 590,000 people
- S大川精螺工業株式会社2026.07.24 announced・Affected Unknown
- S新エフエイコム(岡谷鋼機グループ)2026.07.21 announced・Affected Unknown
- S三浦工業2026.05.18 announced・Affected 5,021 records
- S東山産業株式会社2026.05.12 announced・Affected Unknown
Attack method classification: Exploitation of vulnerabilities(Breaking in through holes in software and devices)
Read the Exploitation of vulnerabilities guide and national trends →