Houghton Mifflin Harcourt Company

Your data was compromised in several of our campaigns throughout the past few months. We urge you to engage with us, it is in your best interests. This is a final warning to reach out by 12 May 2026 before we leak along with several annoying (digital) problems that'll come your way. Make the right decision, don't be the next headline. | Updated: 9 May 2026 | Warning: FINAL WARNING PAY OR LEAK

HMH, or Houghton Mifflin Harcourt, is a long-established publishing company specializing in educational content. They provide a variety of instructional technology, assessments, and other learning materials to schools in over 150 countries. The company also publishes a number of well-known trade and reference works, alongside children's books. Their goal is to foster a lifelong love of learning in every individual they serve.

Founded in 1944, Kendall Hunt Publishing is a publisher of hands-on, inquiry-based science, mathematics, and gifted curricula for grades PreK-12. Their research and standards-based programs are available in both print and digital components that encompass students

Houghton Mifflin Harcourt (HMH) notified the New Hampshire Attorney General on July 1, 2008, regarding a worldwide Internet-based attack on a non-e-commerce website discovered on April 25, 2008. The incident compromised Social Security Numbers for approximately 194 individuals, including 2 New Hampshire residents. HMH retained digital forensics experts, reported the matter to the U.S. Secret Service and state law enforcement, and arranged for two years of free credit monitoring and identity theft insurance for affected individuals. The investigation was ongoing at the time of filing.