phpbb_login_attempts and some other tables without a PRIMARY index

I recently moved my servers to a MySQL Galera cluster, and I am getting loads of these:

[Warning] WSREP: Percona-XtraDB-Cluster doesn't recommend use of DML command on a table (talk3.phpbb_login_attempts) without an explicit primary key with pxc_strict_mode = PERMISSIVE

There must exist PRIMARY keys in every index. My MySQL cluster works only because I set pxc_strict_mode = PERMISSIVE, which should be avoided in a cluster.

Affected tables:

• phpbb_login_attempts
• phpbb_topics_watch
• phpbb_user_group
• phpbb_poll_votes
• phpbb_poll_options
• phpbb_user_notifications