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Cloudflare ’s inspection of tens of thousands of pages that were leaked from its reverse - proxy servers and cached by search engines revealed a " large number " of instances of internal Cloudflare cookies and headers .
 ( data breach: were leaked,  pages: victim, tens of thousands: number of victim, its reverse - proxy servers: victim) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: phishing, data breach, ransom, discover vulnerability, patch vulnerability, Arguments type: vulnerable system, capabilities, vulnerability, number of victim, issues addressed, compromised data, damage amount, common vulnerabilities and exposures, victim, patch number, number of data, tool, discoverer, time, purpose, place, payment method, releaser, vulnerable system version, attacker, supported platform, patch, price, vulnerable system owner, trusted entity, attack pattern. 
Text: {0} 
Answer:
 ( data breach: were leaked,  pages: victim, tens of thousands: number of victim, its reverse - proxy servers: victim) 