KDDI email-system credential leak affecting Japanese ISPs
Data Leak
Summary
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A KDDI email-system breach exposed customer credentials across six Japanese ISPs, putting up to 14.22 million email addresses and passwords at risk. The compromise was detected on June 17 and publicly disclosed on June 23, making this a large-scale credential-exposure event. KDDI says it has modified the system and is urging affected customers to change passwords.
Cases
Related Happenings
KDDI Corporation hit by network compromise
Incident
H score92
First: 24.06.2026 15:45
Last: 24.06.2026 15:45
Sources 1
How related:
In a public statement released on June 23, KDDI Corporation said an unauthorized actor unlawfully gained access to an email system it provides to several Japanese ISPs, meaning that data linked to customers of these email services may have leaked.
About this happening:
KDDI Corporation confirmed an email-system breach that exposed customer credentials across six Japanese ISPs, putting account access at risk. The intrusion was detecte...
KDDI Corporation hit by network compromise
IncidentHow related: In a public statement released on June 23, KDDI Corporation said an unauthorized actor unlawfully gained access to an email system it provides to several Japanese ISPs, meaning that data linked to customers of these email services may have leaked.
About this happening: KDDI Corporation confirmed an email-system breach that exposed customer credentials across six Japanese ISPs, putting account access at risk. The intrusion was detecte...
Latest development: 08.07.2026 14:24
Attackers breached the KDDI email platform used by five Japanese ISPs on May 16 after exploiting a zero-day vulnerability in third-party software, exposing email addresses and passwords across the affected service providers.
Askul records leak tied to RansomHouse ransomware attack
Data Leak
H score49
First: 16.12.2025 01:13
Last: 16.12.2025 01:13
Sources 1
About this happening:
The Askul Corporation data leak now matters because RansomHouse stole about 740,000 records from the company’s October ransomware attack, expanding the blast radiu...
Askul records leak tied to RansomHouse ransomware attack
Data LeakAbout this happening: The Askul Corporation data leak now matters because RansomHouse stole about 740,000 records from the company’s October ransomware attack, expanding the blast radiu...
Nikkei Inc. Slack data leak exposing 17,368 users' names, email addresses, and chat histories
Data Leak
H score35
First: 06.11.2025 00:16
Last: 06.11.2025 00:16
Sources 1
About this happening:
Nikkei Inc. disclosed a Slack data leak affecting 17,368 registered users, exposing names, email addresses, and chat histories. The leak followed an unauthorized ext...
Nikkei Inc. Slack data leak exposing 17,368 users' names, email addresses, and chat histories
Data LeakAbout this happening: Nikkei Inc. disclosed a Slack data leak affecting 17,368 registered users, exposing names, email addresses, and chat histories. The leak followed an unauthorized ext...
Timeline
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24.06.2026 15:45 1 articles · 21d ago
Unauthorized access detected in KDDI email system
Exploitation ObservedKDDI detected unauthorized access to an email system it provides to several Japanese ISPs and assessed that the actor exploited a vulnerability in third-party software used in the email system.
Show sources
- KDDI Breach Affects Six Japanese ISPs, Exposes 14.2 Email Credentials — www.infosecurity-magazine.com — 24.06.2026 15:45
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23.06.2026 03:00 3 articles · 23d ago
KDDI confirms breach exposing up to 14.22 million email credentials across six Japanese ISPs
Initial DisclosureKDDI publicly confirmed the breach, said up to 14.22 million email addresses and passwords were likely compromised across six Japanese ISPs, notified the Personal Information Protection Commission and Japan’s Ministry of Internal Affairs and Communications, and urged affected customers to change passwords while countermeasures were being implemented.
Show sources
- KDDI Breach Affects Six Japanese ISPs, Exposes 14.2 Email Credentials — www.infosecurity-magazine.com — 24.06.2026 15:45
- KDDI Breach Affects Six Japanese ISPs, Exposes 14.2 Email Credentials — www.infosecurity-magazine.com — 24.06.2026 15:45
- Data breach exposes up to 14.2 million email logins at six ISPs — www.bleepingcomputer.com — 28.06.2026 17:13