Asterisk contains a NULL pointer dereference flaw in the 'handle_request_info()' function [channels/chan_sip.c] that may allow a remote denial of service when the 'automon' feature is enabled (disabled by default). With a specially crafted sequence of SIP packets, a remote attacker can cause the service to crash.

Upgrade to version 1.6.2.21 or higher or 1.8.7.2 or higher, as it has been reported to fix this vulnerability. In addition, the vendor has released a patch for some older versions.

• CVE ID: 2011-4598 (see also: NVD)
• Secunia Advisory ID: 47059 47273
• Related OSVDB ID: 77597
• Vendor Specific Advisory URL: http://downloads.asterisk.org/pub/security/AST-2011-014.html
• Mail List Post: http://openwall.com/lists/oss-security/2011/12/09/3
  http://openwall.com/lists/oss-security/2011/12/09/4
• Vendor Specific News/Changelog Entry: http://www.debian.org/security/2011/dsa-2367

• Kristijan Vrban