STNet（専用ネットワーク）Data breach / unauthorized access incident
- Occurred on
- Unconfirmed
- Announced on
- January 21, 2026
- Severity
- SCompromise of deep personal data or usable credentials.
- Scale
- 20,846 people
- Main impact
- It has been reported that the names and contact details of 20,846 personnel, and IDs and passwords for customer systems, may have been leaked from a dedicated network.
- Information involved
- Email addressUser / member IDPasswordPhone numberFull nameDate of birth
- Cause / key point
- Unauthorized intrusion using remote-access configuration files stored on a server.
- Industry
- IT & telecom
- Listing / capital
- UnlistedParent company: 四国電力(東証プライム 9507)
STNet is a subsidiary of 四国電力.
- Last updated
- October 20, 2026
Stock price reaction to the disclosure四国電力・親会社 / 東証プライム 9507
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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)
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