# Django 5.2.16 documentation

# Django 4.0.9 release notes

February 1, 2023

Django 4.0.9 fixes a security issue with severity “moderate” in 4.0.8.

## 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.