The SIP channel driver in Asterisk Open Source 1.2.x before 1.2.34, 1.4.x before 1.4.26.1, 1.6.0.x before 1.6.0.12, and 1.6.1.x before 1.6.1.4; Asterisk Business Edition A.x.x, B.x.x before B.2.5.9, C.2.x before C.2.4.1, and C.3.x before C.3.1; and Asterisk Appliance s800i 1.2.x before 1.3.0.3 does not use a maximum width when invoking sscanf style functions, which allows remote attackers to cause a denial of service (stack memory consumption) via SIP packets containing large sequences of ASCII decimal characters, as demonstrated via vectors related to (1) the CSeq value in a SIP header, (2) large Content-Length value, and (3) SDP.

References

• https://nvd.nist.gov/vuln/detail/CVE-2009-2726
• http://downloads.digium.com/pub/security/AST-2009-005.html
• http://labs.mudynamics.com/advisories/MU-200908-01.txt
• http://secunia.com/advisories/36227
• http://www.securityfocus.com/archive/1/505669/100/0/threaded
• http://www.securityfocus.com/bid/36015
• http://www.securitytracker.com/id?1022705
• http://www.vupen.com/english/advisories/2009/2229