The Oncology Institute Patient Data Compromised via Third-Party Vendor
The Oncology Institute, a publicly traded cancer care provider, was notified on May 20, 2026, by Kroll (acting as a third-party administrator for a vendor) that an unauthorized actor had accessed systems containing patient data. The incident appears to have affected multiple other healthcare providers as well, stemming from a breach in the healthcare supply chain involving a billing-software provider.
Signal context
First seen: May 20, 2026
Last updated: Jun 29, 2026
Status: Public signal
Key points
- The Oncology Institute was notified of patient data compromise on May 20, 2026.
- The breach originated from a third-party vendor, likely a billing-software provider.
- The incident may have impacted multiple healthcare providers.
Signal analysis
BetaThis analysis groups the signal by industry, likely incident action and impacted security area. It helps compare this signal with other published signals without treating the labels as final determinations.
Sector: Information
Likely country: Location not provided
The feed marks multiple actor roles. Treat this as a review signal rather than a final attribution.
- Source type: outside the affected organization
- Source type: supplier or third-party involvement
Impact area: Confidentiality
Likely asset: User or customer data
- 26 signals in the same sector
- 90 signals with the same likely impact area
- 1 signal linked to this organization/domain
External sources
Third-Party Cyberattack Impacts Patient Information at The Oncology Institutehttps://securityaffairs.com/146549/data-breach/the-oncology-institute-data-breach.htmlPublic source from securityaffairs.com.
The Oncology Institute reports patient data potentially exposed in third-party vendor breachhttps://www.scmagazine.com/brief/the-oncology-institute-reports-patient-data-potentially-exposed-in-third-party-vendor-breachPublic source from scmagazine.com.
Biggest Cyber Attacks, Data Breaches, Ransomware Attacks of May 2026https://www.cm-alliance.com/cybersecurity-blog/biggest-cyber-attacks-data-breaches-ransomware-attacks-of-may-2026Public source from cm-alliance.com.
2026 Data Breaches: Cybersecurity Incidents Explained - PKWAREhttps://www.pkware.com/blog/2026-data-breachesPublic source from pkware.com.
Related signals
Grouped by why the signal is relevant.
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JCOM Co., Ltd., a Japanese internet service provider, was impacted by a data breach originating from an email system provided by KDDI Corporation. Threat actors gained unauthorized access to this shared system by exploiting a vulnerability in third-party software. This led to the potential exposure of up to 14.2 million email addresses and passwords across all affected ISPs. JCOM customers' email addresses and passwords may have been compromised.
Polymarket Suffers $3 Million Crypto Drain via Third-Party Vendor Compromise
Prediction market platform Polymarket disclosed a breach where hackers compromised a third-party vendor. The attackers injected malicious code into the Polymarket website for some users, leading to the draining of approximately $3 million in pUSD (USDC-backed) from at least 11 user wallets. The stolen funds were subsequently swapped and moved to Ethereum. Polymarket has contained the incident, committed to full refunds for affected users, and is in the process of notifying victims. This incident highlights supply-chain vulnerabilities in web frontends and crypto platforms.