Digium announced today a Remote Crash Vulnerability in the SIP Channel Driver affecting recent versions of Asterisk 1.4 and 1.6 branches. The full Advisory can be read directly from the Asterisk Project Security Advisory:

Description: When configured with pedantic=yes the SIP channel driver performs extra request URI checking on an INVITE received as a result of a SIP spiral. As part of this extra checking the headers from the outgoing SIP INVITE sent and the received SIP INVITE are compared. The code incorrectly assumes that the string for each header passed in will be non-NULL in all cases. This is incorrect because if no headers are present the value passed in will be NULL.

The values passed into the code are now checked to be non-NULL before being compared.

Resolution: Upgrade to revision 174082 of the 1.4 branch, 174085 of the 1.6.0 branch, 174086 of the 1.6.1 branch, or one of the releases noted below.

The pedantic option in the SIP channel driver can also be turned off to prevent this issue from occurring.

Affected Versions

1.4.x (Versions 1.4.22, 1.4.23,
1.6.0.x (All versions prior to
1.6.1.x (All versions prior to
C.x.x (Only version C.2.3)

If you need assistance in updating or reviewing your Asterisk installation, please contact Team Forrest today.