Cheyenne & Arapaho Tribes Listed by rhysida Ransomware Group: Ransomware Claim — What’s Alleged & What To Do

On February 17, 2026, the Cheyenne & Arapaho Tribes appeared on a listing associated with the Rhysida ransomware group. The entry indicated that internal files had been taken during a ransomware incident, though the number of individuals affected and the precise contents of those files remain undisclosed. The practical stakes center on the possibility that records held by a tribal government could contain personal or administrative information belonging to members and staff. When such material surfaces in connection with a ransomware operation, the main concerns are unauthorized access to sensitive details and potential disruption of tribal services that rely on those systems.

Breaking down the breach

The incident was reported on February 17, 2026, when the Cheyenne & Arapaho Tribes appeared on a site maintained by the Rhysida group. The listing stated that internal files had been exfiltrated during a ransomware attack. No figure has been released for the number of people affected, and no additional technical details such as the initial access method or the volume of data have been made public.

Inside rhysida

Rhysida is a ransomware group that has conducted operations since 2023. Public reporting describes the group as using encryption to disrupt systems while also copying data and threatening its release if a ransom is not paid. The group maintains a site where it lists organizations it claims to have targeted. In this case the listing of the Cheyenne & Arapaho Tribes constitutes an unverified claim by the group; no independent confirmation of the data’s authenticity or scope has been provided.

Who is Cheyenne & Arapaho Tribes?

The Cheyenne and Arapaho Tribes form a federally recognized united nation of the Tsistsistas (Cheyenne) and Hinono'ei (Arapaho) peoples, whose historic alliance dates to the early nineteenth century. As a tribal government the organization administers programs that serve its members, including health, education, housing and other public services. These functions require the collection and storage of personal and administrative records.

What data was at risk

The only detail released is that internal files were allegedly exfiltrated. The exact categories of information contained in those files have not been disclosed. Organizations of this type routinely hold member enrollment data, contact information, financial or benefits records, and operational documents; however, whether any of these specific categories were involved remains unconfirmed.

Why it matters

Exposure of internal files from a tribal government can affect both individuals and the delivery of services. Members may face risks associated with the misuse of personal information, while the organization may experience operational delays if systems were encrypted or taken offline. Because the scale and sensitivity of the material are not yet known, the full extent of these effects cannot be assessed at present.

If your data was in this claimed breach

Individuals who believe their information may have been involved should monitor financial accounts and official correspondence for unusual activity. Enabling multi-factor authentication on any accounts linked to the tribes or to government services is a standard precaution. Readers may also run a free exposure scan of their email address against known breach data to check for prior appearances of their information.

AICompiled with AI assistance from public sources and published under our editorial standards.