Pagure 5.2 leaks API keys by e-mailing them to users. Few e-mail servers validate TLS certificates, so it is easy for man-in-the-middle attackers to read these e-mails and gain access to Pagure on behalf of other users. This issue is found in the API token expiration reminder cron job in files/api_key_expire_mail.py; disabling that job is also a viable solution. (E-mailing a substring of the API key was an attempted, but rejected, solution.)