Django 4.1.12 release notes

October 4, 2023

Django 4.1.12 fixes a security issue with severity “moderate” in 4.1.11.

CVE-2023-43665: Denial-of-service possibility in django.utils.text.Truncator

Following the fix for CVE 2019-14232, the regular expressions used in the implementation of django.utils.text.Truncator’s chars() and words() methods (with html=True) were revised and improved. However, these regular expressions still exhibited linear backtracking complexity, so when given a very long, potentially malformed HTML input, the evaluation would still be slow, leading to a potential denial of service vulnerability.

The chars() and words() methods are used to implement the truncatechars_html and truncatewords_html template filters, which were thus also vulnerable.

The input processed by Truncator, when operating in HTML mode, has been limited to the first five million characters in order to avoid potential performance and memory issues.