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.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:NI:NA:L5.3/CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L