Jan Juergens discovered a buffer overflow in the parser for SMS messages in Asterisk.
An additional change was backported, which is fully described in <http://downloads.asterisk.org/pub/security/AST-2013-007.html>
With the fix for AST-2013-007, a new configuration option was added in order to allow the system adminitrator to disable the expansion of dangerous functions (such as SHELL()) from any interface which is not the dialplan. In stable and oldstable this option is disabled by default. To enable it add the following line to the section '[options]' in /etc/asterisk/asterisk.conf (and restart asterisk)
live_dangerously = no
For the oldstable distribution (squeeze), this problem has been fixed in version 1:22.214.171.124-2+squeeze12.
For the stable distribution (wheezy), this problem has been fixed in version 1:126.96.36.199~dfsg1-3+deb7u3.
For the testing distribution (jessie), this problem has been fixed in version 1:11.7.0~dfsg-1.
For the unstable distribution (sid), this problem has been fixed in version 1:11.7.0~dfsg-1.
We recommend that you upgrade your asterisk packages.