Dentsu Subsidiary Breached, Employee Data Stolen

A Dentsu subsidiary, Merkle, was breached by an unidentified threat actor, with Dentsu reporting that files containing information about current and former employees were stolen from Merkle’s network. According to Dentsu's disclosure, the stolen data is said to include bank and payroll details, salary information, National Insurance numbers, and personal contact details, and the firm has begun notifying potentially affected staff.

Dentsu said it detected unusual activity, activated incident response protocols, and temporarily took some systems offline before bringing them back online; the company also said it engaged a cybersecurity firm and notified law enforcement, the ICO, and the National Cyber Security Centre. To support those impacted, Dentsu is offering a year of credit and Dark Web monitoring.

The disclosure warned that stolen data could be used for phishing or identity fraud, and urged those affected to review financial statements for unauthorised activity. October 29, 2025, Dark Reading reported the incident from Alexander Culafi.