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.
Severity
CVSS 3.0
5.3 medium
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS
4.6% chance of exploitation in the next 30 days; higher than 91% of CVEs (scores of 2026-10-31)