CVE-2011-3279: Cisco IOS

High severity, CVSS 7.8. EPSS: 2.6% chance of exploitation in the next 30 days.

The provider-edge MPLS NAT implementation in Cisco IOS 12.1 through 12.4 and 15.0 through 15.1, and IOS XE 3.1.xSG, allows remote attackers to cause a denial of service (device reload) via a malformed SIP packet to UDP port 5060, aka Bug ID CSCti98219.

Affected products

• Cisco IOS: from 12.1, up to and including 12.4; from 15.0, up to and including 15.1
• Cisco IOS XE: version 3.1.0sg only; version 3.1.1sg only

Published 2011-10-03. Last modified 2026-06-16.