Healthcare

Medium

investigation open

Updated about 2 months ago

Cornerstone Behavioral Healthcare Data Breach

▼ Key takeaways

•Reports suggest a potential breach involving Cornerstone Behavioral Healthcare.
•Discovered on September 1, 2026.
•Possible data exposed: Name, Address, Date of Birth, Health Care Information, Substance Use Disorder Treatment Information, Insurance Information, MaineCare Information, Social Security Number, Appointment Details.
•Affects individuals in: Maine.
•Confirmation level: Confirmed by company.

Breach confirmed

The Cornerstone Behavioral Healthcare breach is confirmed. If you may be affected, add your details below and we will take it from there.

Detailed summary

Cornerstone Behavioral Healthcare, a mental health and substance use treatment provider in Bangor, Maine, discovered a ransomware attack in May 2026. This incident compromised the protected health information of more than 14,800 patients.

Data types affected include names, addresses, dates of birth, health care information, substance use disorder treatment details, insurance and MaineCare information, Social Security numbers, and appointment details. The company confirmed over 14,800 patients were impacted.

Further details, such as consumer notification dates or regulatory filings, have not yet been publicly disclosed.

Data possibly involved

Name
Address
Could be combined with other data for identity theft
Date of Birth
Often used in combination with other data for identity theft
Health Care Information
Substance Use Disorder Treatment Information
Insurance Information
MaineCare Information
Social Security Number
Can be used to open fraudulent accounts and file false tax returns
Appointment Details

Company Response Timeline

Breach Occurred

May 26, 2026

Company Discovered

May 1, 2026

Regulator Notified

Unknown

Consumers Notified

Unknown

-25 days to discover

Breach Verification Status

Reports Only

Complete

Initial dark web reports of potential breach

Company Confirmed

Current

Company has acknowledged the breach

Regulator Confirmed

Confirmed by regulatory authorities

Note: Breach verification can take time. Information may evolve as more details become available from companies and regulators.

Case Status:

Investigation Open

We're actively investigating this case and seeking affected individuals.

Were you affected? Submit your information below.

Were You Affected By This Breach?

If you are a customer or have received a data breach notification, you may submit your information as part of our ongoing investigation. Submitting your information is free and does not obligate you.

Were you in the Cornerstone Behavioral Healthcare breach? Check your email

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Check Your Risk Level

Answer a few questions to understand how this breach might affect you

Do you use Cornerstone Behavioral Healthcare?

Yes

What state are you in?

What should I do?

Change your passwords

Update passwords for the affected service and any accounts using the same password

Enable two-factor authentication

Add an extra layer of security to your accounts

Monitor your accounts

Watch for suspicious activity on your financial and online accounts

Watch for phishing attempts

Be cautious of emails or messages claiming to be from the affected company

Consider a credit freeze

Prevent unauthorized access to your credit report

Scan your email for other exposures

Check whether this address shows up in other known breaches. Free, no account.

Get your info off data-broker sites

Data Shield files removal requests with every broker that accepts an authorized agent, and gives you the exact link or letter for the brokers that only accept requests from you.

See how Data Shield works