薬日本堂株式会社（委託先メールサービス）Data breach / unauthorized access incident
- Occurred on
- Unconfirmed
- Announced on
- March 2, 2026
- Severity
- BIncidents centered on names and contact details.
- Scale
- Unknown
- Main impact
- The company announced that unauthorized access to the spam email filtering service may have allowed a third party to view addresses and contents of quarantined emails, but the number of affected people and incidents has not been disclosed.
- Information involved
- Email address
- Cause / key point
- Unauthorized access to a contracted (third-party) service that was being used.About Supply chain attacks (via vendors & shared services)
- Industry
- Retail & e-commerce
- Listing / capital
- Unlisted
- 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
Related incidents
Browse the database →Incidents sharing the same company, service, attack method or industry (grouped automatically from the disclosures).
Incidents related to "アドレス"
Incidents where the damage spread through the same service or system.
Same attack method
- S第一興商（ビッグエコー等）2026.10.08 announced・Affected 8,631,000 records
- A旭化成セラピューティクス（Pharma DIGITAL）2026.10.06 announced・Affected 514,000 people
- A大和証券2026.10.05 announced・Affected 220,000 records
- CTOPPAN（損保ジャパン）2026.09.29 announced・Affected 177,426 people
- A大東ガス株式会社2026.09.28 announced・Affected 124,000 records
- A大阪大学2026.10.21 announced・Affected 77,851 people
Same industry
- S阪急阪神百貨店（H2O ID等）2026.10.19 announced・Affected 1,260,000 records
- Sパピレス（Renta!）2026.10.19 announced・Affected Unknown
- Sジグザグ（WorldShopping）2026.10.19 announced・Affected 301 people
- Sブックオフグループ(ブックオフコーポレーション)2026.10.09 announced・Affected 6,383,279 people
- Sアクティブ（通販サイト）2026.10.06 announced・Affected 54,916 records
- SMrMax2026.10.06 announced・Affected 1,735,154 people
Attack method classification: Supply chain attacks (via vendors & shared services)(Compromising the provider instead of the user)
Read the Supply chain attacks (via vendors & shared services) guide and national trends →