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Researcher Artem Moskowsky told The Register earlier this week that he stumbled across the vulnerability – which earned him a $ 20,000 bug bounty for reporting it – by accident while looking over the Steam partner portal .
 Researcher Artem Moskowsky: discoverer; earlier this week: time; he: discoverer; the vulnerability: vulnerability
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:
 Researcher Artem Moskowsky: discoverer; earlier this week: time; he: discoverer; the vulnerability: vulnerability