Parse Server email verification resend page leaks user existence

Impact

The Pages route and legacy PublicAPI route for resending email verification links return distinguishable responses depending on whether the provided username exists and has an unverified email. This allows an unauthenticated attacker to enumerate valid usernames by observing different redirect targets. The existing emailVerifySuccessOnInvalidEmail configuration option, which is enabled by default and protects the API route against this, did not apply to these routes.

Patches

The email verification resend routes now respect the emailVerifySuccessOnInvalidEmail option. When set to true (the default), both routes redirect to the success page regardless of the outcome, preventing user enumeration.

Workarounds

There is no known workaround to prevent the information disclosure other than upgrading.