野村證券Data breach / unauthorized access incident
- Occurred on
- October 16, 2026
- Announced on
- October 23, 2026
- Severity
- CLimited data such as email addresses and identifiers.
- Scale
- Unknown
- Main impact
- Due to unauthorized access to a contractor's system, stored subscribers' email addresses and the like may have been leaked externally. It has been announced that portfolio information and securities trading account information are not included.
- Information involved
- Email address
- Cause / key point
- Information may have leaked externally due to unauthorized access to the contractor ユミルリンク's system.About Supply chain attacks (via vendors & shared services)
- Industry
- Finance & insurance
- Listing / capital
- UnlistedParent company: 野村ホールディングス
野村證券 is a major securities company within the 野村ホールディングス group.
- Sources
- Last updated
- October 25, 2026
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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 →