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JAENES
APossible leakJune 12, 2026 announced

日本テレネットData breach / unauthorized access incident

笹尾 祐太朗の写真Reviewed by Yutaro SasaoWritten by Leak Watch editorial team published ・ updated
Occurred on
March 9, 2026
Announced on
June 12, 2026
Severity
AFinancial and HR records — information that easily translates into monetary damage.
Scale
602,000 records
Main impact
There is a risk of leakage affecting CSS contracted operations 60.2万件, BPO contracted operations 40.4万件, etc.; overlap between categories is unknown and no traces of external transfer have been confirmed.
Information involved
Email address
Cause / key point
Intrusion by an external attacker via network equipment.
Industry
IT & telecom
Listing / capital
Unlisted
Sources
Last updated
October 20, 2026
Email addressHow severity is assessed →

Is this incident worth paying attention to?

Written & reviewed

笹尾 祐太朗の写真

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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