What happened
Newsletter platform Substack confirmed that it experienced a data breach that exposed user information stored in its systems. According to the notification sent to impacted individuals, an unauthorized party gained access to some internal support tools that contained email addresses and associated data for users of the platform. Substack indicated that no passwords, payment information, or other highly sensitive financial data were included in the exposed data set. The intrusion was detected by the company’s security team, which immediately initiated incident response procedures to investigate the root cause and scope of the breach. Substack informed affected users via email about the breach, the nature of the exposed data, and steps it was taking to secure internal systems going forward.
Who is affected
Users of Substack, including newsletter creators and subscribers whose email addresses and related metadata were stored in the compromised support tools, are affected through unauthorized exposure of that user information.
Why CISOs should care
The breach illustrates how unauthorized access to internal support platforms and tools can lead to exposure of user identifiers and operational metadata, presenting privacy and account security concerns even when financial credentials are not involved.
3 practical actions
- Audit access to internal support tools. Review which systems contain user data and who can access them.
- Review logging and detection. Ensure monitoring is in place to spot anomalous access to support platforms.
- Communicate incident details clearly. Notify impacted users and provide guidance on potential risks associated with exposed data.