copyparty allows Regex Denial of Service (ReDoS) in the upload listing

Summary The filter parameter for the "Recent uploads" page allows arbitrary Regexes. If this feature is enabled which is the default, an attacker can craft a filter which deadlocks the server. PoC https://127.0.0.1:3923/?ru&filter=.++x Impact The server becomes fully inaccessible for a long time...