第一興商（ビッグエコー等）Data breach / unauthorized access incident
- Occurred on
- Unconfirmed
- Announced on
- October 8, 2026
- Severity
- SCompromise of deep personal data or usable credentials.
- Scale
- 8,631,000 records
- Main impact
- They announced that due to infection of a contractor terminal, approximately 約863.1万件 customer records and 従業員約9.3万件 employee records, totaling 計約872.4万件, may have been exposed. Names, dates of birth, and contact information were affected; customer passwords were not included.
- Information involved
- Email addressPhone numberFull nameDate of birth
- Cause / key point
- A contractor employee's terminal (PC1台) was infected with malware; the contractor is investigating the cause and scope of the damage.About Supply chain attacks (via vendors & shared services)
- Industry
- Services & other
- Listing / capital
- Listed company東証プライム 7458(第一興商)
- Last updated
- October 20, 2026
Stock price reaction to the disclosure第一興商 / 東証プライム 7458
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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: Supply chain attacks (via vendors & shared services)(Compromising the provider instead of the user)
Read the Supply chain attacks (via vendors & shared services) guide and national trends →