asterisk - multiple issues

Paul Belanger reported a vulnerability in Asterisk identified as
AST-2011-008
(CVE-2011-2529)
through which an unauthenticated attacker may crash an Asterisk
server remotely. A package containing a NULL char causes the SIP header parser
to alter unrelated memory structures.

Jared Mauch reported a vulnerability in Asterisk identified as
AST-2011-009
through which an unauthenticated attacker may crash an Asterisk server remotely.
If a user sends a package with a Contact header with a missing left angle
bracket (<) the server will crash. A possible workaround is to disable chan_sip.

The vulnerability identified as
AST-2011-010
(CVE-2011-2535)
reported about an
input validation error in the IAX2 channel driver. An unauthenticated attacker
may crash an Asterisk server remotely by sending a crafted option control frame.

For the oldstable distribution (lenny), this problem has been fixed in
version 1.4.21.2~dfsg-3+lenny5.

For the stable distribution (squeeze), this problem has been fixed in
version 1.6.2.9-2+squeeze3.

For the testing distribution (wheezy), this problem has been fixed in
version 1:1.8.4.3-1.

For the unstable distribution (sid), this problem has been fixed in
version 1:1.8.4.3-1.

We recommend that you upgrade your asterisk packages.