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KDDI: Breach History & DoxxScan™ Rating

KDDI has 2 publicly reported breaches in our tracker. Here is the timeline, what was exposed, and its DoxxScan™ Rating.

KDDI has 2 distinct publicly reported incidents in our tracker, the most recent dated June 2026. The most serious is classified CRITICAL severity, and the incidents together account for roughly 14.2M records. Data described in the associated reports and leak-site claims as potentially involved includes email-addresses, passwords and credentials. Named threat group tied to these claims: alphv. The DoxxScan™ Rating below is an automated estimate of how exposed KDDI’s customers could be if the reported claims are accurate.

65/100

Moderate doxx risk

DoxxScan™ Rating — lower means a higher likelihood that personal data tied to this company is exposed and could be used to dox or target its customers.

PARTLY UNCONFIRMED 1 of the 2 incidents behind this rating is an extortion-group listing, which KDDI has not confirmed and nobody accountable has corroborated. It is weighted down accordingly.

™powered by GalaxyWarden

June 23, 2026HIGH

KDDI Breach Exposes Up to 14.2M Email Logins at 6 Japanese ISPs

Credential & Infostealer Leaks

May 5, 2023HIGH

KKDICOID including companies AICC, JBI, TJFI (part of the kddicom holding company, whose d Listed by alphv Ransomware Group

alphv Ransomware

Data described in the claims

Across these incidents, the data described in the associated reports and threat-actor claims as potentially involved includes: email-addresses, passwords, credentials. These are the categories cited in the reporting/listings, not independently verified by Recent Breaches.

Steps tailored to the data types reported exposed in the incidents above.

• Change the password on that account — and anywhere you reused it — then turn on two-factor authentication (2FA).
• Expect targeted phishing that references this breach — be skeptical of unexpected emails asking you to log in, verify, or pay.
• Your physical address may be circulating — remove yourself from data-broker and people-search sites to lower your doxxing risk.
• Remove your personal information from data-broker sites so the leaked data can’t be combined against you — GalaxyWarden files those removals for you.

This profile is assembled automatically from KDDI’s own tracked incident records — the incidents above, their classified severity, the data types reported exposed, and how recent each event is. Only incidents where information was reported lost count toward either rating; an outage or an advisory with no reported data loss is listed but not scored as exposure. The DoxxScan™ Rating estimates how exposed the company’s customers may be (a lower number means more exposure); the Safety Grade scores its publicly known record (higher = a cleaner known history). Neither is an audit of the company’s current security controls. See the full methodology →

The DoxxScan™ Rating is an automated, informational estimate of how exposed a company’s customers may be if the incidents on its public record are accurate, derived solely from that record — the number of incidents, how recent and severe they were, the sensitivity of the data involved, and who established the incident. Most incidents we track are unverified listings published by ransomware and extortion groups; those are accusations, not established facts, and they count for less. A lower rating indicates a higher likelihood that personal information tied to this company is circulating and could be used to dox or target individuals. It is not an audit, certification, or assessment of the company’s current security controls, and it does not represent present-day risk. It may rely on incomplete or unverified public reports and can change as new information emerges. Recent Breaches and GalaxyWarden are independent and are not affiliated with, and do not endorse, any company named here. Provided for general awareness only — not legal, financial, or security advice. How the rating is calculated →