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Published: 2 November 2023

An issue was discovered in Django 3.2 before 3.2.23, 4.1 before 4.1.13, and 4.2 before 4.2.7. The NFKC normalization is slow on Windows. As a consequence, django.contrib.auth.forms.UsernameField is subject to a potential DoS (denial of service) attack via certain inputs with a very large number of Unicode characters.


is a windows-specific issue



Cvss 3 Severity Score


Score breakdown


Package Release Status
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(windows only)
focal Not vulnerable
(windows only)
jammy Not vulnerable
(windows only)
lunar Not vulnerable
(windows only)
mantic Not vulnerable
(windows only)
trusty Not vulnerable
(windows only)
upstream Not vulnerable
(debian: Only an issue on windows)
xenial Not vulnerable
(windows only)

Severity score breakdown

Parameter Value
Base score 7.5
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact None
Availability impact High
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H