Bitbucket 8.18+ will ship with some more secure default settings. One of these is public/anonymous access. Historically the anonymous/public access feature was enabled by default (and could be disabled by a setting in bitbucket.properties) such that repository administrators could enable public access for a given repository.

Beginning with Bitbucket 8.18 the default will be flipped. For instances that actually require anonymous/public access the following should be set in $BITBUCKET_HOME/shared/bitbucket.properties:

feature.public.access=true

When upgrading an existing instance that needs this feature enabled, you can add this setting prior to upgrade