Updated shadow-utils packages correct a bug that caused the useradd tool to create mail spools with incorrect permissions.
The shadow-utils package includes programs for converting UNIX password files to the shadow password format, plus programs for managing user and group accounts. One of these programs is useradd and is used to create or update new user information. When creating a user account, the version of useradd included in Red Hat Linux 7.2, 7.3, and 8.0 creates a mailbox file with incorrectly-set group ownership. Instead of setting the file's group ownership to the 'mail' group, it is set to the user's primary group. On systems where other users share the same primary group, this would allow those users to be able to read and write other user mailboxes. These erratum packages contain an updated patch to useradd. Where a 'mail' group exists, mailboxes will be created with group 'mail' having read and write permissions. Otherwise the mailbox file will be created without group read and write permissions. All users of Red Hat Linux are advised to update to these erratum packages and to also check the /var/spool/mail directory to ensure that all mailbox files have appropriate permissions.