976
However , if the recent Bitcoin Core software bug had not been patched , a bad actor could have initiated a 51 % attack on the cryptocurrency ’s network at a considerably lower cost .
 patch vulnerability: had not been patched
Please tell me event type and its trigger word from given type options. Output format is "type: trigger".  Option: phishing, data breach, ransom, discover vulnerability, patch vulnerability 
Text: {0} 
Answer:
 patch vulnerability: had not been patched