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jcom.co.jp
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Confidence MediumJun 28, 2026jcom.co.jp

JCOM Affected by KDDI Data Breach, Email Logins Exposed

PatternExternal actor · Hacking · Confidentiality impact

JCOM, an internet service provider, was affected by the data breach at KDDI Corporation, which was disclosed on June 28, 2026. The breach, caused by a vulnerability in third-party software, led to unauthorized access to KDDI's email systems and the potential exposure of email addresses and passwords for up to 14.2 million customers across the affected ISPs, including JCOM.

Signal date
Jun 28, 2026
Updated
Jun 28, 2026
Confidence
Medium
Sources
2 sources
jcom.co.jp logo

Jcom

Sector
Information
Signals
1 linked

Signal context

First seen: Jun 28, 2026

Last updated: Jun 28, 2026

Status: Public signal

Key points

  • Impacted as a user of KDDI's compromised email system.
  • Email addresses and passwords of customers potentially exposed.
  • Disclosure date: June 28, 2026.

Signal analysis

Beta

This analysis groups the signal by industry, likely incident action and impacted security area. It helps compare this signal with other published signals without treating the labels as final determinations.

Affected organization
Jcom logo
Jcom

Sector: Information

Likely country: 🇯🇵 Japan

inferred from company domain

    Estimated
    Threat source
    Hacking activity

    Watch internet-facing systems, credential abuse and exploit activity.

    • Source type: outside the affected organization
    Business impact
    Potential data exposure

    Impact area: Confidentiality

    Likely asset: User or customer data

    Trend context
    75 signals with similar action pattern
    • 32 signals in the same sector
    • 95 signals with the same likely impact area
    • 1 signal linked to this organization/domain
    Mentioned entities
    JcomData DisclosureJCOM AffectedEmail Logins Exposed JCOMKDDI CorporationKDDIISPsJCOM. ImpactedEmailDisclosure

    External sources

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    Grouped by why the signal is relevant.

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