CyrusOne data breach: 373K accounts exposed
Severity: medium · Patch status: no-fix-needed · Since 2026-10-07
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. Exposed data: email addresses, employers, job titles, names, phone numbers, physical addresses, support tickets. The breach dates from Aug 5, 2026; Have I Been Pwned loaded it on Oct 7, 2026.
What to do
- If you had a CyrusOne account, change its password and the password of any other account that reused it.
- Turn on multi-factor authentication wherever it is offered.
- Check whether your addresses are in this breach at https://haveibeenpwned.com.
- Expect targeted phishing that quotes the leaked details; verify any unexpected contact out of band.
Sources
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