Recommended - update to latest Piccolo version

[dantownsend]

We were recently made aware of a potential security issue with Piccolo, which has now been patched in piccolo==0.121.0.

The severity is low, so there's no need to be overly worried, but upgrading is recommended.

The issue was with BaseUser.login. When attempting to login a valid username, the code would take longer than for an invalid username. So if you tried logging in with a username a bunch of times, statistically it would give you an indication whether that username exists in the database.

It doesn't give the attacker access to any other information, and first they must guess a username and try logging in a bunch of times. Piccolo Admin, which is the main user of BaseUser.login, has rate limiting middleware built-in to help guard against these sorts of automated login attempts. We released piccolo_admin==0.58.0, which makes the rate limiting more aggressive, so we recommend upgrading that too.

To put it all in perspective, some websites will disclose whether a username exists after a failed login attempt, as a matter of good UX (see the discussion here). But as we didn't explicitly want this behaviour, it needed fixing.