The issue is related to the `django.utils.text.Truncator` class, specifically the `chars()` and `words()` methods. When these methods are passed the `html=True` argument, they can be extremely slow to evaluate certain inputs due to a catastrophic backtracking vulnerability in a regular expression. This vulnerability can be exploited to cause a denial of service. The `chars()` and `words()` methods are used to implement the `truncatechars html` and `truncatewords html` template filters.