Two security vulnerabilities were discovered in Heirloom mailx, an implementation of the "mail" command: CVE-2004-2771 mailx interprets interprets shell meta-characters in certain email addresses. CVE-2014-7844 An unexpected feature of mailx treats syntactically valid email addresses as shell commands to execute. Shell command execution can be re-enabled using the "expandaddr" option. Note that this security update does not remove all mailx facilities for command execution, though. Scripts which send mail to addresses obtained from an untrusted source should use the "--" separator before the email addresses , or they should be changed to invoke "mail -t" or "sendmail -i -t" instead, passing the recipient addresses as part of the mail header.