Django 1.8.19 release notes

March 6, 2018

Django 1.8.19 fixes two security issues in 1.18.18.

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 a catastrophic backtracking vulnerability in a regular expression. The urlize() function is used to implement the urlize and urlizetrunc template filters, which were thus vulnerable.

The problematic regular expression is 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.