An issue was discovered in Django 2.0 before 2.0.3, 1.11 before 1.11.11, and 1.8 before 1.8.19. 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.

Affected: Ubuntu:14.04:LTS: python-django, Ubuntu:16.04:LTS: python-django

James Davis discovered that Django incorrectly handled certain template filters. A remote attacker could possibly use this issue to cause Django to consume resources, resulting in a denial of service.