大和証券Data breach / unauthorized access incident
- Occurred on
- October 2, 2026
- Announced on
- October 5, 2026
- Severity
- AFinancial and HR records — information that easily translates into monetary damage.
- Scale
- 220,000 records
- Main impact
- Unauthorized access to the server handling outsourced inquiry management may have exposed personal data of about 110,000 individuals, including names, email addresses, and securities account numbers (approximately 220,000 records including inquiry information). No fraudulent transactions have been confirmed.
- Information involved
- Email addressUser / member IDCard & payment dataFull name
- Cause / key point
- Unauthorized access by a third party to the server of the contractor (スカラコミュニケーションズ) occurred from the night of 10月2日 to the morning of 10月3日.About Supply chain attacks (via vendors & shared services)
- Industry
- Finance & insurance
- Listing / capital
- UnlistedParent company: 大和証券グループ本社(東証プライム 8601)
大和証券 is a subsidiary of 大和証券グループ本社.
- Sources
- Last updated
- October 20, 2026
Stock price reaction to the disclosure大和証券グループ本社・親会社 / 東証プライム 8601
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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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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 →