Nikkei

Disclosed Nov 4, 202517,368 affectedConfirmed

Nikkei Slack compromise exposes data of 17,368 people

Nikkei said its Slack workspace was compromised, potentially exposing names, email addresses and chat histories of 17,368 employees and business partners registered on Slack.

What is known

People affected	17,368 (as reported by the organization)
Disclosed	Nov 4, 2025
Attack	Hacking
Data exposed	NamesEmailsMessages
Sector	Media · JP
Status	Confirmed

Sources

Newsbleepingcomputer.com

Media giant Nikkei reports data breach impacting 17,000 people

The organizationnikkei.co.jp

Nikkei announcement

Notices filed

TotalNov 4, 2025

Research17,368 people

Other breaches at Nikkei

Nikkei discloses breaches of employees’ Microsoft, Google email accountsNikkei discloses breaches of employees’ Microsoft, Google email accountsPhishing1.8M affectedMediaJPUnverifiedOct 6

History of this record

Added2026-09-25

First recordedby seedSource

First seen 2026-09-25 (Research), confirmed by Research. Record counts are as reported. Not legal advice.

Everything about Nikkei