Modoc Medical Center data breach: files downloaded over nine days in January 2026

What happened at Modoc Medical Center?

Modoc says it secured its systems, investigated with cybersecurity specialists and reported the event to federal law enforcement and regulators. It then had a third party review the files to find out what they held, whom they concerned and how to reach those people. The letter calls that review time-intensive.

Date	What the letter and the regulators' records say
January 19 to 27, 2026	Unknown actor downloads files
January 27, 2026	Modoc becomes aware of the access
March 27, 2026	Report to HHS (29,688)
September 22, 2026	Logged in Massachusetts (10 residents)

The HHS report came two months after detection. The Massachusetts entry came six months after that.

What information was involved?

Modoc Medical Center's sample letter leaves the list of data items blank. For the 10 Massachusetts residents in Modoc Medical Center's notice, the state's record marks Social Security numbers and financial accounts as breached. Modoc says it has no indication of identity theft or fraud.

What is Modoc offering?

Item	Detail from the letter
Service	Experian IdentityWorks credit monitoring and identity restoration; the sample leaves the term as 12 or 24 months
Questions	888-780-4985, 6:00 a.m. to 6:00 p.m. Pacific Time, Monday to Friday; or by mail at 1111 North Nagle Street, Alturas, CA 96101

The guide to credit monitoring offers sets Modoc Medical Center's offer beside other letters.

Was Modoc Medical Center hit by ransomware?

Not by Modoc's own account, which describes files viewed or taken and says nothing about encryption. HIPAA Journal reports that the Worldleaks ransomware and data extortion group claimed responsibility, and that it is unclear whether ransomware was involved. The same report describes Modoc as a 12-bed critical access hospital and rural healthcare system in Alturas, California, and says the unauthorized access was detected on January 27, 2026.

What information was involved in the Modoc breach?

Modoc's website notice, updated on April 3, 2026, lists what the mailed sample leaves blank: name, Social Security number, medical information, credit card numbers and other general demographic information, varying by person. Anyone whose letter lists a card number can ask the card issuer for a new one.

The website notice puts the window the same way as the letter, January 19 to January 27, 2026, and says the information was viewed or taken in that time.

How many people were affected by the Modoc Medical Center breach?

29,688 people, the number Modoc gave the federal health privacy office on March 27, 2026.

Record	What it counts	Number
HHS Office for Civil Rights	People affected	29,688
Massachusetts consumer affairs office	Massachusetts residents	10

Was my information in the Modoc Medical Center data breach?

If you got a letter from Modoc Medical Center, your information was in the reviewed files. The website notice gives a second toll-free line for questions, (844) 403-4542, Monday to Friday from 8:00 a.m. to 5:30 p.m. Central time, and the mailing address 1111 North Nagle Street, Alturas, CA 96101. HIPAA Journal reports that people were offered 12 or 24 months of credit monitoring, matching the term the sample letter leaves open.

What the documents leave open

• How the unknown actor got in, and whether the files Worldleaks claims have been published.
• How many letters went out, and when, beyond the Massachusetts date.

With 29,688 people, Modoc Medical Center's report is the 100th largest of the 415 open 2026 reports in the ranking of 2026 healthcare breaches reported to HHS.