CPossible leakSeptember 16, 2026 announced

アイスタイル（@cosme）Data breach / unauthorized access incident

Reviewed by Yutaro SasaoWritten by Leak Watch editorial teamSeptember 16, 2026 published ・ October 20, 2026 updated

Occurred on: September 2, 2026
Announced on: September 16, 2026
Severity: CLimited data such as email addresses and identifiers.
Scale: 10,997 people
Main impact: Email addresses, delivery settings, user IDs, etc. for 10,997 people were accessible via an internal-sharing URL and were deleted about 20 minutes later; names and similar information were not included.
Information involved: Email addressUser / member ID
Cause / key point: Misconfigured file publication settings on an external file transfer service.
Industry: Retail & e-commerce
Listing / capital: Listed company東証プライム 3660(アイスタイル)
Sources: @cosmeご登録の個人情報の漏えいの可能性に関するお知らせとお詫び
Last updated: October 20, 2026

Stock price reaction to the disclosureアイスタイル / 東証プライム 3660

2026.08.27 〜 2026.10.07Loading…

Stock information is reference data based on Yahoo Finance and may be delayed. This site does not solicit or advise investment and does not guarantee the accuracy or completeness of this information. We accept no liability for any investment decision based on it.

How severity is assessed →

Is this incident worth paying attention to?

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: October 20, 2026

Written by:Leak Watch editorial team (AI-assisted drafts verified against sources by the editorial team) · Reviewer profile · Request a correction