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 your bsd-mailx packages.

mailx is the traditional command-line-mode mail user agent. Even if you don't use it, it may be required by other programs.

bsd-mailx on Debian Linux

This check tests the installed software version using the apt package manager.

• http://www.debian.org/security/2014/dsa-3104.html

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Updated on 2015-03-25