Breach date: 2026-08-05. Added to this index: 2026-10-07. Accounts affected: about 373K. Domain: cyrusone.com.
What happened
In August 2026, data centre operator CyrusOne was the target of a ShinyHunters "pay or leak" extortion attempt. The group subsequently published data allegedly obtained from the company, which included 373k unique email addresses across records relating to users, sales leads and CyrusOne employees. The data largely consisted of corporate contact information, including names, physical addresses, phone numbers and job titles. It also included support tickets and other information related to the organisation's operations.
Breach data sourced from Have I Been Pwned, used under CC BY 4.0. Additional breach metadata provided by XposedOrNot. DataExposed is an independent service and is not affiliated with or endorsed by either.
What was exposed
Email addresses: The email address you used to register or log in. It is the most common field in breaches because it doubles as your username on most sites.
Employers: The name of the company or organisation you work for, collected by professional networks, job sites, insurers, lenders and many signup forms.
Job titles: Your role or position, such as accounts payable officer, nurse or IT administrator, recorded by professional networks, business software, event registrations and marketing lists.
Names: Your first name, surname and sometimes middle name or initials, as you gave them when you signed up. It appears in almost every breach because nearly every account asks for it.
Phone numbers: Your mobile or landline number, collected at signup for contact, delivery updates, marketing and two-factor codes.
Physical addresses: Your residential, postal, billing or delivery address, stored by retailers, utilities, banks, government services and almost any company that sends you something.
Support tickets: Messages, chat transcripts, attachments and notes from customer support conversations, including problems you reported and details you shared to prove who you are.
What to do now
Check whether your own address is in this dataset with the free email breach check.
Review the accounts connected to this service and turn on two-factor authentication.
Turn on two-factor authentication on your email account first, because it is the reset path for everything else.
Treat calls and messages that quote real details about you as hostile until you verify them another way.
Frequently asked questions
What data was leaked in the CyrusOne breach?
The CyrusOne breach exposed Email addresses, Employers, Job titles, Names, Phone numbers, Physical addresses, Support tickets. About 373K accounts were affected.
Was I affected by the CyrusOne breach?
Run the free email breach check with the address you used on that service. It will tell you whether your address appears in this dataset.
What should I do about the CyrusOne breach?
Treat any message that quotes details from this breach as suspicious, turn on two-factor authentication, and consider removing your details from people-search sites if your address or phone was included.