--- title: KDDI Breach Exposes Up to 14.2 Million Email Logins at... description: Japanese telecom KDDI disclosed a data breach affecting up to 14.2 million email accounts across six ISPs including STNet, JCOM, NIFTY, and BIGLOBE. Attackers... canonical: https://daily.dev/posts/kddi-breach-exposes-up-to-14-2-million-email-logins-at-six-isps-1qyhm9fag twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: KDDI Breach Exposes Up to 14.2 Million Email Logins at Six ISPs | daily.dev og:description: Japanese telecom KDDI disclosed a data breach affecting up to 14.2 million email accounts across six ISPs including STNet, JCOM, NIFTY, and BIGLOBE. Attackers... og:url: https://daily.dev/posts/kddi-breach-exposes-up-to-14-2-million-email-logins-at-six-isps-1qyhm9fag og:image: https://api.daily.dev/og/posts/1QYhm9Fag.png og:image:alt: KDDI Breach Exposes Up to 14.2 Million Email Logins at Six ISPs og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # KDDI Breach Exposes Up to 14.2 Million Email Logins at Six ISPs **[Security Boulevard](https://daily.dev/sources/securityboulevard)** · 3 min read · 0 upvotes · 0 comments ## Summary Japanese telecom KDDI disclosed a data breach affecting up to 14.2 million email accounts across six ISPs including STNet, JCOM, NIFTY, and BIGLOBE. Attackers exploited a vulnerability in unnamed third-party software on KDDI's shared email system, potentially exposing email addresses and passwords. Some passwords were stored hashed or encrypted, but KDDI did not disclose the method or proportion stored in plaintext. The breach was discovered June 17 and reported to Japanese regulators. Affected customers are advised to reset passwords and enable 2FA. CISOs are warned about downstream risks from shared provider infrastructure, credential stuffing, and business dependence on personal ISP email accounts for recovery workflows. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Data breach exposes up to 14.2 million email logins at six ISPs](https://daily.dev/posts/data-breach-exposes-up-to-14-2-million-email-logins-at-six-isps-seex7uzig) · BleepingComputer · 0 upvotes · 0 comments - [Telco giant KDDI says data breach affects over 12 million people](https://daily.dev/posts/telco-giant-kddi-says-data-breach-affects-over-12-million-people-mu8uzzc5b) · BleepingComputer · 0 upvotes · 0 comments --- Tags: [#authentication](https://daily.dev/tags/authentication), [#data-breach](https://daily.dev/tags/data-breach) [View this post on daily.dev](https://daily.dev/posts/kddi-breach-exposes-up-to-14-2-million-email-logins-at-six-isps-1qyhm9fag) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"KDDI Breach Exposes Up to 14.2 Million Email Logins at Six ISPs","url":"https://daily.dev/posts/kddi-breach-exposes-up-to-14-2-million-email-logins-at-six-isps-1qyhm9fag","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/kddi-breach-exposes-up-to-14-2-million-email-logins-at-six-isps-1qyhm9fag"},"datePublished":"2026-06-29T10:00:18.030Z","dateModified":"2026-06-29T10:00:44.708Z","description":"Japanese telecom KDDI disclosed a data breach affecting up to 14.2 million email accounts across six ISPs including STNet, JCOM, NIFTY, and BIGLOBE. 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