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 truncatechars_html and 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, 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 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 django.utils.html.escape().

CVE-2019-14234: SQL injection possibility in key and index lookups for JSONField/HStoreField

Key and index lookups for django.contrib.postgres.fields.JSONField and key lookups for HStoreField were subject to SQL injection, using a suitably crafted dictionary, with dictionary expansion, as the **kwargs passed to QuerySet.filter().

CVE-2019-14235: Potential memory exhaustion in django.utils.encoding.uri_to_iri()

If passed certain inputs, django.utils.encoding.uri_to_iri() could lead to significant memory usage due to excessive recursion when re-percent-encoding invalid UTF-8 octet sequences.

uri_to_iri() now avoids recursion when re-percent-encoding invalid UTF-8 octet sequences.

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 (#30628).
• Fixed a migration crash on PostgreSQL when adding a check constraint with a contains lookup on DateRangeField or DateTimeRangeField, if the right hand side of an expression is the same type (#30621).
• Fixed a regression in Django 2.2 where auto-reloader crashes if a file path contains nulls characters ('\x00') (#30506).
• Fixed a regression in Django 2.2 where auto-reloader crashes if a translation directory cannot be resolved (#30647).