===========================
Django 5.2.12 release notes
===========================

*March 3, 2026*

Django 5.2.12 fixes a security issue with severity "moderate" and a security
issue with severity "low" in 5.2.11. It also fixes one bug related to support
for Python 3.14.

CVE-2026-25673: Potential denial-of-service vulnerability in ``URLField`` via Unicode normalization on Windows
==============================================================================================================

The :class:`~django.forms.URLField` form field's ``to_python()`` method used
:func:`~urllib.parse.urlsplit` to determine whether to prepend a URL scheme to
the submitted value. On Windows, ``urlsplit()`` performs
:func:`NFKC normalization <python:unicodedata.normalize>`, which can be
disproportionately slow for large inputs containing certain characters.

``URLField.to_python()`` now uses a simplified scheme detection, avoiding
Unicode normalization entirely and deferring URL validation to the appropriate
layers. As a result, while leading and trailing whitespace is still stripped by
default, characters such as newlines, tabs, and other control characters within
the value are no longer handled by ``URLField.to_python()``. When using the
default :class:`~django.core.validators.URLValidator`, these values will
continue to raise :exc:`~django.core.exceptions.ValidationError` during
validation, but if you rely on custom validators, ensure they do not depend on
the previous behavior of ``URLField.to_python()``.

This issue has severity "moderate" according to the :ref:`Django security
policy <severity-levels>`.

CVE-2026-25674: Potential incorrect permissions on newly created file system objects
====================================================================================

Django's file-system storage and file-based cache backends used the process
``umask`` to control permissions when creating directories. In multi-threaded
environments, one thread's temporary umask change can affect other threads'
file and directory creation, resulting in file system objects being created
with unintended permissions.

Django now applies the requested permissions via :func:`~os.chmod` after
:func:`~os.mkdir`, removing the dependency on the process-wide umask.

This issue has severity "low" according to the :ref:`Django security policy
<severity-levels>`.

Bugfixes
========

* Fixed :exc:`NameError` when inspecting functions making use of deferred
  annotations in Python 3.14 (:ticket:`36903`).
