Madera Community Hospital data breach: a May 2025 intrusion, and letters in July 2026

What happened at Madera Community Hospital?

The hospital says it worked with outside cybersecurity experts from the start. Its investigation did not find definitive proof that files with personal or health information were taken, and it has seen no sign the data was released. It collected the potentially affected files and had a data-review firm analyse them. The results arrived in April 2026, after which it worked on finding current contact details.

Date	What the letter and the regulators' records say
Late May 2025	Unauthorized access for two days; May 28 and 29 on the California record
May 29, 2025	Suspicious activity detected
June 2025	Forensic investigation finds the access; no files identified as taken
April 2026	Data-review results received
July 13, 2026	Report to HHS (150,810)
July 14, 2026	Notice recorded by California
July 17, 2026	Logged in Massachusetts (1 resident)

Letters went out about 14 months after detection. The hospital says law enforcement was notified and did not delay the notice.

What information was involved?

Each letter fills in the reader's items, and the website notice lists the categories (below). Massachusetts' single record marks medical records as breached. The guide to healthcare provider breach notices compares other hospitals' letters.

What is Madera Community Hospital offering?

A complimentary membership to Experian IdentityWorks, for the number of months printed on each letter, with an enrollment deadline on each letter. A separate version of the letter offers the same service for children.

Item	Detail from the letter
Provider	Experian IdentityWorks
Questions	(844) 958-8906, Monday to Friday, 8:00 a.m. to 5:30 p.m. Central Time, excluding major U.S. holidays

Did Madera Community Hospital pay a ransom?

The hospital's own notice says it did not have to decide. The group that claimed the attack asked for an extortion payment, then dropped the demand when it learned its victim was a hospital, telling the hospital it did not want to harm patients. The notice does not name the group.

That is also why the hospital's account changed over time. Its June 2025 investigation found no files taken, but "subsequent developments" led it to believe a third party had acquired files from part of the network. The hospital then gathered the files it believed were affected and sent them to a data-review firm, whose results came back in April 2026.

What information was involved in the Madera breach?

The website notice gives the full list, which the mailed letter leaves blank: name, birthdate, contact information, login credentials, government identification numbers such as a Social Security number, financial account details, limited medical information such as treatment and health insurance details, and limited biometric information. Not every person had every item exposed, and the hospital says it has found no sign that the data was shared or released.

A person whose letter lists login credentials should change that password wherever it was used.

How many people were affected by the Madera Community Hospital breach?

150,810 people, the number the hospital gave the federal health privacy office. SecurityWeek reported the same figure when the letters went out, describing the hospital as a not-for-profit provider serving Madera County.

Record	What it counts	Number
HHS Office for Civil Rights	People affected	150,810
Massachusetts consumer affairs office	Massachusetts residents	1

The hospital mailed letters on July 15, 2026 to everyone it had a valid mailing address for, and posted the website notice for the rest.

Was my information in the Madera Community Hospital data breach?

If you got a letter from Madera Community Hospital in July 2026, your information was in the reviewed files. If you were a patient and did not get one, the hospital may not have had a current address for you; the website notice exists for that case, and the phone line in the table above takes questions. The guide to healthcare provider breach notices explains how to read a hospital's letter.

What the documents leave open

• What the "subsequent developments" were.
• Which group claimed the attack.
• Which data elements apply to which patients.
• How the third party got in.