France's Tchap Messaging Platform Breached by Hijacked Account

Authorities blocked the compromised account and opened a forensic investigation to determine what public chat content was exposed.

Overview

France’s cybersecurity agency ANSSI detected the intrusion on June 7 and DINUM identified and immediately blocked the hijacked user account used to access Tchap.
Officials say the attacker’s access was limited to public chat rooms that are not end‑to‑end encrypted and that private, encrypted conversations should remain secure.
An individual posting online claimed to have taken roughly 73,000 accounts, 643,000 messages and about 13.5 GB of media but French authorities have not verified those figures.
DINUM has notified CNIL, alerted all Tchap users about the public-room exposure risk, and is analyzing event logs to map which conversations and files the account could reach.
Tchap is a state-managed platform made mandatory for civil servants in 2025, which increased its user base and makes the investigation important for government operations and personal data protection.