Cornerstone Behavioral Healthcare Data Breach Class Action Investigation

A ransomware attack on Cornerstone Behavioral Healthcare exposed Social Security numbers and substance use disorder treatment records belonging to patients. If you received a data breach notification letter from Cornerstone Behavioral Healthcare, our data breach lawyers want to hear from you.

What Happened?

According to a notice published by Cornerstone Behavioral Healthcare, the organization was hit by a ransomware attack that was discovered and stopped on the same day. The breach occurred on May 26, 2026. Information exposed in the breach reportedly included names, addresses, other contact information, dates of birth, health care information, substance use disorder treatment information, insurance and MaineCare information, and Social Security numbers. Affected individuals were notified directly by Cornerstone Behavioral Healthcare. The notice states that the personal information of 2,830 individuals may have been compromised. A continued investigation later revealed that an appointment reminder log covering an additional 12,000 individuals may also have been accessed.

If you are a patient who received care from Cornerstone Behavioral Healthcare, you may be entitled to compensation. Fill out the form below to see if you qualify.

Steps To Take If You Were Affected

1. Monitor your credit reports and financial accounts for suspicious activity
2. Consider placing a fraud alert or credit freeze with all three major credit bureaus
3. Be alert to phishing emails or calls referencing the breach
4. Change passwords on any affected accounts and enable two-factor authentication
5. Keep a copy of your data breach notification letter for your records