The Nextcloud iOS Files app allows users of iOS to interact with Nextcloud, a self-hosted productivity platform. Prior to version 4.9.2, the application can be used without providing the 4 digit PIN code. Nextcloud iOS Files app should be upgraded to 4.9.2 to receive the patch. No known workarounds are available.
https://hackerone.com/reports/2245437
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-j8g7-88vv-rggv