NULL pointer dereference in the daap_reply_groups function in src/httpd_daap.c in owntone-server through commit 5e6f19a (newer commit after version 28.2) allows remote attackers to cause a Denial of Service.
https://github.com/owntone/owntone-server/commit/d857116e4143a500d6a1ea13f4baa057ba3b0028