In SonarQube before 10.4 and 9.9.4 LTA, encrypted values generated using the Settings Encryption feature are potentially exposed in cleartext as part of the URL parameters in the logs (such as SonarQube Access Logs, Proxy Logs, etc).
In SonarQube 8.4.2.36762, an external attacker can achieve authentication bypass through SonarScanner. With an empty value for the -D sonar.login option, anonymous authentication is forced. This allows creating and overwriting public and private projects via the /api/ce/submit endpoint.
SonarQube 8.4.2.36762 allows remote attackers to discover cleartext SMTP, SVN, and GitLab credentials via the api/settings/values URI. NOTE: reportedly, the vendor's position for SMTP and SVN is "it is the administrator's responsibility to configure it.