株式会社講談社Data breach / unauthorized access incident
- Occurred on
- July 30, 2026
- Announced on
- August 3, 2026
- Severity
- BIncidents centered on names and contact details.
- Scale
- 3,812 records
- Main impact
- Unauthorized access to a corporate email account resulted in contact information for up to 3,812 people being stolen, and spoofed emails were sent to 553 of those email addresses.
- Information involved
- Email addressAuth tokenFull name
- Cause / key point
- Authentication credentials were stolen after clicking a phishing email link impersonating a business partner, leading to unauthorized access to a corporate email account.About Targeted email & phishing
- Industry
- Media & entertainment
- Listing / capital
- Unlisted
講談社 is not publicly listed.
- Sources
- Last updated
- October 20, 2026
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:
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: Targeted email & phishing(Fake emails and sites that steal credentials)
Read the Targeted email & phishing guide and national trends →