An issue was discovered in Django 1.11.x before 1.11.23, 2.1.x before 2.1.11, and 2.2.x before 2.2.4. If django.utils.text.Truncators 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 product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Django | Djangoproject | 1.11 (including) | 1.11.23 (excluding) |
| Django | Djangoproject | 2.1 (including) | 2.1.11 (excluding) |
| Django | Djangoproject | 2.2 (including) | 2.2.4 (excluding) |
| Red Hat OpenStack Platform 13.0 (Queens) | RedHat | python-django-0:1.11.27-1.el7ost | * |
| Red Hat OpenStack Platform 13.0 (Queens) for RHEL 7.6 EUS | RedHat | python-django-0:1.11.27-1.el7ost | * |
| Red Hat OpenStack Platform 15.0 (Stein) | RedHat | python-django-0:2.1.11-1.el8ost | * |
| Python-django | Ubuntu | bionic | * |
| Python-django | Ubuntu | devel | * |
| Python-django | Ubuntu | disco | * |
| Python-django | Ubuntu | esm-infra-legacy/trusty | * |
| Python-django | Ubuntu | esm-infra/bionic | * |
| Python-django | Ubuntu | esm-infra/focal | * |
| Python-django | Ubuntu | esm-infra/xenial | * |
| Python-django | Ubuntu | focal | * |
| Python-django | Ubuntu | jammy | * |
| Python-django | Ubuntu | kinetic | * |
| Python-django | Ubuntu | lunar | * |
| Python-django | Ubuntu | mantic | * |
| Python-django | Ubuntu | noble | * |
| Python-django | Ubuntu | oracular | * |
| Python-django | Ubuntu | plucky | * |
| Python-django | Ubuntu | trusty | * |
| Python-django | Ubuntu | trusty/esm | * |
| Python-django | Ubuntu | xenial | * |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.