user_oidc app is an OpenID Connect user backend for Nextcloud. A malicious user could send a malformed login link that would redirect the user to a provided URL after successfully authenticating. It is recommended that the Nextcloud User OIDC app is upgraded to 6.1.0.
https://hackerone.com/reports/2720030
https://github.com/nextcloud/user_oidc/pull/961
https://github.com/nextcloud/user_oidc/commit/c923428d51972f6d04636c6accbecdec0c1b88e9
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-784j-x2g5-4g7q