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. The django.utils.html.urlize() function was extremely slow to evaluate certain inputs due to catastrophic backtracking vulnerabilities in two regular expressions (only one regular expression for Django 1.8.x). The urlize() function is used to implement the urlize and urlizetrunc template filters, which were thus vulnerable.
www.securityfocus.com/bid/103361
access.redhat.com/errata/RHSA-2018:2927
access.redhat.com/errata/RHSA-2019:0051
access.redhat.com/errata/RHSA-2019:0082
access.redhat.com/errata/RHSA-2019:0265
github.com/advisories/GHSA-r28v-mw67-m5p9
lists.debian.org/debian-lts-announce/2018/03/msg00006.html
usn.ubuntu.com/3591-1/
www.debian.org/security/2018/dsa-4161
www.djangoproject.com/weblog/2018/mar/06/security-releases/