CVE-2024-39317: Wagtail regular expression denial-of-service via search query parsing

A bug in Wagtail’s parse_query_string would result in it taking a long time to process suitably crafted inputs. When used to parse sufficiently long strings of characters without a space, parse_query_string would take an unexpectedly large amount of time to process, resulting in a denial of service.

In an initial Wagtail installation, the vulnerability can be exploited by any Wagtail admin user. It cannot be exploited by end users. If your Wagtail site has a custom search implementation which uses parse_query_string, it may be exploitable by other users (e.g. unauthenticated users).