CVE-2009-2726

Severity: high (CVSS 7.8 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 6.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2009-08-12 · updated 2026-06-16
Weakness: CWE-770

Description

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; from c.2.0 through c.2.4.1; from c.3.0 before c.3.1; from 1.2.0 before 1.2.34; from 1.4.0 before 1.4.26.1; from 1.6.0 before 1.6.0.12 — fixed in 1.2.34, 1.4.26.1, 1.6.0.12, 1.6.1.4, b.2.5.9, c.3.1
Digium S800I Firmware: from 1.2.0 before 1.3.0.3 — fixed in 1.3.0.3

How to fix

Upgrade to a fixed version: Digium Asterisk 1.2.34, 1.4.26.1, 1.6.0.12, 1.6.1.4; Digium S800I Firmware 1.3.0.3. Check the vendor advisory for mitigations.

References

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