This update for nextcloud to 18.0.4 fixes the following issues:
Security issues fixed:
CVE-2020-8154: Fixed an XSS vulnerability when opening malicious PDFs (NC-SA-2020-018 boo#1171579).
CVE-2020-8155: Fixed a direct object reference vulnerability that allowed attackers to remotely wipe devices of other users (NC-SA-2020-019 boo#1171572).