2025 Japan Exchange Group — IIJ Secure MX email security incident; JPX ultimately reported no mailbox leak after review
Data compromised
None confirmed exfiltrated per JPX closing notice
Technical writeup
JPX disclosed a third-party IIJ Secure MX cyber event that initially raised potential corporate email exposure; an 23 Apr 2025 update states no email leak confirmed after investigation—indexed as enterprise vendor email-security supply-chain stress.
Root cause
Attack against outsourced secure email/MX service provider