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Last week , we reported about a cryptographer who found a supposed vulnerability in WhatsApp and later gave an interview to The Guardian explaining the matter .
 a supposed vulnerability: vulnerability; WhatsApp: vulnerable system; a cryptographer: discoverer; Last week: time
Given event type and trigger, please tell me the arguments of all the listed option. Output format is "name1: role1; name2: role2". 
Event type: discover vulnerability 
  Option: vulnerable system owner, vulnerability, capabilities, time, vulnerable system version, discoverer, common vulnerabilities and exposures, supported platform, vulnerable system 
Text: {0} 
Answer:
 a supposed vulnerability: vulnerability; WhatsApp: vulnerable system; a cryptographer: discoverer; Last week: time