CVE-2018-7537 Django Denial-of-service possibility in truncatechars_html and truncatewords_html template filters

What is CVE-2018-7537?

CVE-2018-7537 is a medium-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 9 Mar 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-185

Which versions are affected by CVE-2018-7537?

7 open source packages ship an affected version, including django and Django. It affects 3 products.

Products include Canonical Ubuntu Linux, Debian Debian Linux, Djangoproject Django.

How do I fix CVE-2018-7537?

Upgrade django to a fixed version for your release line: 1.11.11, 1.8.19 or 2.0.3.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2018-7537 being exploited?

There is no known exploitation of CVE-2018-7537 in the wild and no public exploit code.

Other vulnerabilities in Canonical Ubuntu Linux

• CVE-2020-11651 SaltStack Salt Authentication Bypass Exploited Critical 9.8
• CVE-2020-7247 OpenSMTPD Remote Code Execution Exploited Critical 9.8
• CVE-2019-16928 Exim Out-of-bounds Write Exploited Critical 9.8
• CVE-2018-6789 Exim Buffer Overflow Exploited Critical 9.8
• CVE-2015-2590 Oracle Java SE and Java SE Embedded Remote Code Execution Exploited Critical 9.8

All Canonical Ubuntu Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2018-7537, DEBIAN-CVE-2018-7537, GHSA-2f9x-5v75-3qv4, PYSEC-2018-6, UBUNTU-CVE-2018-7537.