Disclosure context

About shinyhunters

Based on the limited publicly available information, shinyhunters appears to be a recently emerged ransomware group first observed in October 2025, primarily motivated by financial gain through extortion activities targeting organizations across multiple sectors. The group's origin and potential affiliations remain unclear due to their recent emergence, and there is insufficient public documentation to determine whether they operate as a Ransomware-as-a-Service model or as an independent entity. Their attack methodology and specific technical capabilities have not been extensively documented by major threat intelligence firms, though their targeting pattern suggests a broad opportunistic approach rather than sector-specific specialization. The group has reportedly victimized approximately 77 organizations, with primary targeting focused on the United States, France, Japan, Germany, and Australia, showing particular interest in consumer services, technology, financial services, transportation and logistics, and education sectors. Given the group's very recent emergence in late 2025, there are no widely reported major campaigns or high-profile incidents documented by established security research organizations, and no known law enforcement actions have been publicly reported against this group. The current operational status of shinyhunters remains active based on available reporting, though comprehensive threat intelligence profiles from major security firms like Mandiant, CrowdStrike, or government agencies have not yet been published due to the group's recent appearance in the threat landscape. The group has been linked to 108 public disclosures across our corpus. First observed on a leak site on October 3, 2025; most recent post May 12, 2026. The operation is currently active.

Timeline of this disclosure

May 9, 2026Houghton Mifflin Harcourt Company listed by shinyhunterson the group's public leak site

Sector and geography

This disclosure adds to ransomware activity in the Education sector, which has 694 disclosures indexed across all operators we track. Geographically, Houghton Mifflin Harcourt Company is reported in US, a country with 2,713 ransomware disclosures in our corpus.

How we know this. Darkfield monitors public ransomware leak sites continuously, archiving every new disclosure and the data later released against the victim. Each entry on this page is sourced from the operator's own publication and cross-checked against complementary OSINT feeds (RansomLook, ransomware.live, RansomWatch). We do not collect or host stolen data — only the metadata, timestamps and screenshots needed to make the public disclosure searchable and accountable. Records here are corrected when the original post is edited, retracted, or merged with another disclosure.

Ransomware victim disclosure

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Houghton Mifflin Harcourt Company

Claimed by shinyhunters · listed 12 days ago

11d

Age

since listed · data leaked

Status timeline

Listed
May 9, 2026
Data leaked

At a glance

Group: shinyhunters
Status: Data leaked
Country: US
Sector: Education
Listed on leak site: May 9, 2026

About the victim

AI dossier — public-source company profile

Houghton Mifflin Harcourt (HMH) is a US-based K-12 learning company headquartered in Boston, Massachusetts, offering core curriculum, supplemental, and intervention products across literacy, math, and other subjects. The company serves schools and districts nationwide with both print and digital educational materials, including programs such as Into Reading, Go Math!, and Read 180. HMH is one of the largest educational publishers in the United States.

Industry: K-12 Educational Publishing & Learning Solutions
Address: 125 High Street, Boston, MA 02110, USA
Employees: 5001-10000
Founded: 1832

Attack summary

Severity: high — HMH serves K-12 students at scale, meaning exfiltrated data likely includes PII for minors (students) and educators — a regulated, sensitive category. ShinyHunters is a credible, historically active threat actor with confirmed prior large-scale exfiltrations. The 'data_published' disclosure status and multi-campaign claim elevate severity, though no explicit proof files or confirmed data categories are listed, stopping short of 'critical'.

ShinyHunters claims to have exfiltrated data from Houghton Mifflin Harcourt across multiple campaigns over several months and is issuing a final warning to pay before publicly leaking the data along with unspecified additional disruptive actions. The post indicates data has been collected but not yet fully published, with a stated deadline of 12 May 2026.

high

Data the group says was taken

AI dossier — extracted from the leak post

Unspecified exfiltrated company data
Potentially student and educator records
Potentially internal business data

What the group claims

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

Sources

Victim sitehmhco.com

Source

Indexed 12 days ago

This page surfaces a public ransomware disclosure indexed by Darkfield. Original posts come from the operator's own leak site; we cross-check against ransomware.live, RansomLook and RansomWatch where applicable. Share this URL freely.