CVE-2023-6152: Email Validation Bypass And Preventing Sign Up From Email's Owner

Email validation can easily be bypassed because verify_email_enabled option enable email validation at sign up only. A user changing it’s email after signing up (and verifying it) can change it without verification in /profile. This can be used to prevent legitimate owner of the email address from signing up.

Another way to prevent email’s owner from signing up is by setting Username as an email: When a new user is registrering, they can set two different email addresses in the Email and Username field, technically having 2 email addresses (because Grafana handles usernames and emails the same in some situations), but only the former is validated.

Here user a prevents owner of bar@example.com to signup.