Eight people across the US who registered to use Ashley Madison are suing the cheating website after it was hacked.
Detailed personal information on millions of users was leaked in the hack, including credit card numbers and sexual preferences.
The lawsuits were filed by people who had signed up to Ashley Madison in California, Texas, Missouri, Georgia, Tennessee and Minnesota.
They all seek class-action status to represent the estimated 37 million registered Ashley Madison users.
The lawsuits, which seek unspecified damages, claim negligence, breach of contract and privacy violations.
They claim Ashley Madison failed to take reasonable steps to protect the security of its users, including those who paid a special fee to have their information deleted.
Ashley Madison is offering a $500,000 (€437,462.54) reward for information leading to the arrest of a group that hacked the site.
