Debian DSA-3104-1 Critical Vulnerability in Bsd-Mailx Execution Risk

It was discovered that bsd-mailx, an implementation of the "mail"
command, had an undocumented feature which treats syntactically valid
email addresses as shell commands to execute.

Users who need this feature can re-enable it using the "expandaddr" in
an appropriate mailrc file. This update also removes the obsolete -T
option. An older security vulnerability, CVE-2004-2771, had already
been addressed in the Debian's bsd-mailx package.

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 (such as a web form) should use the
"--" separator before the email addresses (which was fixed to work
properly in this update), or they should be changed to invoke
"mail -t" or "sendmail -i -t" instead, passing the recipient addresses
as part of the mail header.

For the stable distribution (wheezy), this problem has been fixed in
version 8.1.2-0.20111106cvs-1+deb7u1.

We recommend that you upgrade...