CVE-2009-2726: Digium Asterisk

High severity, CVSS 7.8. EPSS: 6.5% chance of exploitation in the next 30 days.

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.

Affected products

• Digium Asterisk: before b.2.5.9 (fixed in b.2.5.9); from c.2.0, up to and including c.2.4.1; from c.3.0, before c.3.1 (fixed in c.3.1); from 1.2.0, before 1.2.34 (fixed in 1.2.34); from 1.4.0, before 1.4.26.1 (fixed in 1.4.26.1); from 1.6.0, before 1.6.0.12 (fixed in 1.6.0.12); …
• Digium s800i Firmware: from 1.2.0, before 1.3.0.3 (fixed in 1.3.0.3)

Published 2009-08-12. Last modified 2026-06-16.