Asterisk Remote Crash Vulnerability in SIP channel driver, AST-2009-002 - Remote Crash Vulnerability in SIP channel driver, has been fixed in two Asterisk upgrades that we just posted.
The bug, 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.
The security advisory is available at;
Friday, March 13, 2009