CVE-2009-2051: Cisco IOS

High severity, CVSS 7.8. EPSS: 3.4% chance of exploitation in the next 30 days.

Cisco IOS 12.2 through 12.4 and 15.0 through 15.1, Cisco IOS XE 2.5.x and 2.6.x before 2.6.1, and Cisco Unified Communications Manager (aka CUCM, formerly CallManager) 4.x, 5.x before 5.1(3g), 6.x before 6.1(4), and 7.x before 7.1(2) allow remote attackers to cause a denial of service (device reload or voice-services outage) via a malformed SIP INVITE message that triggers an improper call to the sipSafeStrlen function, aka Bug IDs CSCsz40392 and CSCsz43987.

Affected products

• Cisco IOS: from 12.2, up to and including 12.4; from 15.0, up to and including 15.1
• Cisco IOS XE: from 2.5.0, up to and including 2.6.1
• Cisco Unified Communications Manager: from 5.0, before 5.1\(3g\) (fixed in 5.1\(3g\)); from 6.1\(1\), before 6.1\(4\) (fixed in 6.1\(4\)); from 7.1, before 7.1\(2\) (fixed in 7.1\(2\))

Published 2009-08-27. Last modified 2026-06-16.