Frigate NVR Vulnerable to Denial of Service Attack via Large Unicode Filenames

Summary

Frigate is a network video recorder (NVR) with realtime local object detection for IP cameras. Below 0.13.2 Release, when uploading a file or retrieving the filename, a user may intentionally use a large Unicode filename which would lead to a application-level denial of service. This is due to no limitation set on the length of the filename and the costy use of the Unicode normalization with the form NFKD under the hood of `secure_filename()`.