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Facebook discovered a security issue that allowed hackers to access information that could have let them take over around 50 million accounts , the company announced on Friday .
 Facebook: discoverer; a security issue: vulnerability; allowed hackers to access information: capabilities; let them take over around 50 million accounts: capabilities
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:
 Facebook: discoverer; a security issue: vulnerability; allowed hackers to access information: capabilities; let them take over around 50 million accounts: capabilities