ユミルリンク（メール配信システム）Data breach / unauthorized access incident
- Occurred on
- Unconfirmed
- Announced on
- October 19, 2026
- Severity
- BIncidents centered on names and contact details.
- Scale
- 9,000,000 records
- Main impact
- ユミルリンク has confirmed unauthorized access to 5 email-delivery-related systems and data extraction; the extracted information is estimated to total 約900万件, including email addresses. Details are under investigation.
- Information involved
- Email addressAuth token
- Cause / key point
- Confirmed data extraction associated with unauthorized access.
- Industry
- IT & telecom
- Listing / capital
- Listed company東証グロース 4372(ユミルリンク)
- Last updated
- October 20, 2026
Stock price reaction to the disclosureユミルリンク / 東証グロース 4372
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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: Unauthorized access (method undisclosed)(Breached, but the technique was not identified or disclosed)
Read the Unauthorized access (method undisclosed) guide and national trends →