Several vulnerabilities have been discovered in Asterisk, an Open Source PBX and telephony toolkit: CVE-2011-4597 Ben Williams discovered that it was possible to enumerate SIP user names in some configurations. Please see README.Debian for more information on how to update your installation. CVE-2011-4598 Kristijan Vrban discovered that Asterisk can be crashed with malformed SIP packets if the "automon" feature is enabled.