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JAENES
BPartial leak confirmedDecember 24, 2025 announced

横須賀学院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
Unconfirmed
Announced on
December 24, 2025
Severity
BIncidents centered on names and contact details.
Scale
Unknown
Main impact
It was found that, due to a ransomware attack, some personal information stored on the server (excluding photos and videos) was leaked, and students, parents, and alumni may be subject to secondary harm such as fraudulent contact or bogus billing.
Information involved
Not specified in the disclosure
Cause / key point
Data leakage from the server due to a ransomware attack.About Ransomware
Industry
Education
Listing / capital
Non-profit corporation

Determined to be a private school.

Sources
Last updated
October 20, 2026
How 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: Ransomware(Encrypting data and demanding a ransom)

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