When etcupdate encounters conflicts while merging files, it saves a version containing conflict markers in /var/db/etcupdate/conflicts. This version does not preserve the mode of the input file, and is world-readable. This applies to files that would normally have restricted visibility, such as /etc/master.passwd. An unprivileged local user may be able to read encrypted root and user passwords from the temporary master.passwd file created in /var/db/etcupdate/conflicts. This is possible only when conflicts within the password file arise during an update, and the unprotected file is deleted when conflicts are resolved.
https://security.freebsd.org/advisories/FreeBSD-SA-25:03.etcupdate.asc