堺市（電子申請システム）Data breach / unauthorized access incident
- Occurred on
- October 29, 2026
- Announced on
- November 5, 2026
- Severity
- CLimited data such as email addresses and identifiers.
- Scale
- 290,000 records
- Main impact
- Up to approximately 290,000 email addresses registered in 堺市's electronic application system may have been exposed. The city is investigating whether addresses were included in the leak and has disabled the mail-sending function, suspending acceptance confirmation emails and similar notifications.
- Information involved
- Email address
- Cause / key point
- Unauthorized access to the email delivery service, attributed to a Web server vulnerability and issues in the system environment that enabled the intrusion.About Exploitation of vulnerabilities
- Industry
- Government & municipal
- Listing / capital
- Government / public body
- Sources
- Last updated
- November 7, 2026
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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
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Attack method classification: Exploitation of vulnerabilities(Breaking in through holes in software and devices)
Read the Exploitation of vulnerabilities guide and national trends →