Nextcloud Mail is an email application for the nextcloud personal cloud product. Affected versions of Nextcloud mail would log user passwords to disk in the event of a misconfiguration. Should an attacker gain access to the logs complete access to affected accounts would be obtainable. It is recommended that the Nextcloud Mail is upgraded to 1.12.1. Operators should inspect their logs and remove passwords which have been logged. There are no workarounds to prevent logging in the event of a misconfiguration.
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-63m3-w68h-3wjg
https://github.com/nextcloud/mail/pull/6488/commits/ab9ade57fbc1f465ffe905248f93f328d638d7e5