Health Net began notifying 1,236,902 members that their data was breached in a nationwide cyberattack.
The California insurer, whose parent company is Centene, is part of a nationwide attack on data transfer file service provider Accellion, according to a March 24 notice letter.
Cybercriminals were able to view or save victims' data that was stored by Accellion between Jan. 7 and Jan. 25.
Breached information may include birthdates, insurance numbers, addresses and more.
Other companies affected in this data breach include Kroger Pharmacy, Palo Alto, Calif.-based Stanford Medicine, Trillium Community Health Plan and more.