==========================
Django 2.2.4 release notes
==========================

*August 1, 2019*

Django 2.2.4 fixes security issues and several bugs in 2.2.3.

CVE-2019-14232: Denial-of-service possibility in ``django.utils.text.Truncator``
================================================================================

If ``django.utils.text.Truncator``'s ``chars()`` and ``words()`` methods
were passed the ``html=True`` argument, they were extremely slow to evaluate
certain inputs due to a catastrophic backtracking vulnerability in a regular
expression. The ``chars()`` and ``words()`` methods are used to implement the
:tfilter:`truncatechars_html` and :tfilter:`truncatewords_html` template
filters, which were thus vulnerable.

The regular expressions used by ``Truncator`` have been simplified in order to
avoid potential backtracking issues. As a consequence, trailing punctuation may
now at times be included in the truncated output.

CVE-2019-14233: Denial-of-service possibility in ``strip_tags()``
=================================================================

Due to the behavior of the underlying ``HTMLParser``,
:func:`django.utils.html.strip_tags` would be extremely slow to evaluate
certain inputs containing large sequences of nested incomplete HTML entities.
The ``strip_tags()`` method is used to implement the corresponding
:tfilter:`striptags` template filter, which was thus also vulnerable.

``strip_tags()`` now avoids recursive calls to ``HTMLParser`` when progress
removing tags, but necessarily incomplete HTML entities, stops being made.

Remember that absolutely NO guarantee is provided about the results of
``strip_tags()`` being HTML safe. So NEVER mark safe the result of a
``strip_tags()`` call without escaping it first, for example with
:func:`django.utils.html.escape`.

Bugfixes
========

* Fixed a regression in Django 2.2 when ordering a ``QuerySet.union()``,
  ``intersection()``, or ``difference()`` by a field type present more than
  once results in the wrong ordering being used (:ticket:`30628`).

* Fixed a migration crash on PostgreSQL when adding a check constraint
  with a ``contains`` lookup on
  :class:`~django.contrib.postgres.fields.DateRangeField` or
  :class:`~django.contrib.postgres.fields.DateTimeRangeField`, if the right
  hand side of an expression is the same type (:ticket:`30621`).

* Fixed a regression in Django 2.2 where auto-reloader crashes if a file path
  contains nulls characters (``'\x00'``) (:ticket:`30506`).

* Fixed a regression in Django 2.2 where auto-reloader crashes if a translation
  directory cannot be resolved (:ticket:`30647`).