django -- denial-of-service attack

Django project reports:

Django’s forms library includes field types which perform
regular-expression-based validation of email addresses and
URLs. Certain addresses/URLs could trigger a pathological
performance case in these regular expression, resulting in
the server process/thread becoming unresponsive, and consuming
excessive CPU over an extended period of time. If deliberately
triggered, this could result in an effectively
denial-of-service attack.