Django 2.0.3 release notes

March 6, 2018

Django 2.0.3 fixes two security issues and several bugs in 2.0.2. Also, the latest string translations from Transifex are incorporated.

CVE-2018-7536: Denial-of-service possibility in urlize and urlizetrunc template filters

The django.utils.html.urlize() function was extremely slow to evaluate certain inputs due to catastrophic backtracking vulnerabilities in two regular expressions. The urlize() function is used to implement the urlize and urlizetrunc template filters, which were thus vulnerable.

The problematic regular expressions are replaced with parsing logic that behaves similarly.

CVE-2018-7537: Denial-of-service possibility in truncatechars_html and truncatewords_html template filters

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 backtracking problem in the regular expression is fixed.

Bugfixes

• Fixed a regression that caused sliced QuerySet.distinct().order_by() followed by count() to crash (#29108).
• Prioritized the datetime and time input formats without %f for the Thai locale to fix the admin time picker widget displaying “undefined” (#29109).
• Fixed crash with QuerySet.order_by(Exists(...)) (#29118).
• Made Q.deconstruct() deterministic with multiple keyword arguments (#29125). You may need to modify Q’s in existing migrations, or accept an autogenerated migration.
• Fixed a regression where a When() expression with a list argument crashes (#29166).
• Fixed crash when using a Window() expression in a subquery (#29172).
• Fixed AbstractBaseUser.normalize_username() crash if the username argument isn’t a string (#29176).