Django 1.11.x before 1.11.19, 2.0.x before 2.0.11, and 2.1.x before 2.1.6 allows Uncontrolled Memory Consumption via a malicious attacker-supplied value to the django.utils.numberformat.format() function.
https://www.openwall.com/lists/oss-security/2019/02/11/1
https://www.djangoproject.com/weblog/2019/feb/11/security-releases/
https://www.debian.org/security/2019/dsa-4476
https://usn.ubuntu.com/3890-1/
https://seclists.org/bugtraq/2019/Jul/10
https://groups.google.com/forum/#%21topic/django-announce/WTwEAprR0IQ