3120
One of the largest trading posts on the Dark Web , AlphaBay , has rewarded a researcher for disclosing the existence of a vulnerability which allowed him to steal over 200,000 private messages exchanged between users and sellers .
 the existence of a vulnerability: vulnerability; a researcher: discoverer
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:
 the existence of a vulnerability: vulnerability; a researcher: discoverer