# Django 4.2.11 documentation

# Django 4.1.6 release notes

February 1, 2023

Django 4.1.6 fixes a security issue with severity “moderate” and a bug in 4.1.5.

## CVE-2023-23969: Potential denial-of-service via `Accept-Language` headers

The parsed values of `Accept-Language` headers are cached in order to avoid repetitive parsing. This leads to a potential denial-of-service vector via excessive memory usage if large header values are sent.

In order to avoid this vulnerability, the `Accept-Language` header is now parsed up to a maximum length.

## Bugfixes

- Fixed a bug in Django 4.1 that caused a crash of model validation on `UniqueConstraint` with ordered expressions (#34291).