CVE-2012-3950: Cisco IOS

High severity, CVSS 7.1. EPSS: 1.5% chance of exploitation in the next 30 days.

The Intrusion Prevention System (IPS) feature in Cisco IOS 12.3 through 12.4 and 15.0 through 15.2, in certain configurations of enabled categories and missing signatures, allows remote attackers to cause a denial of service (device reload) via DNS packets, aka Bug ID CSCtw55976.

Affected products

• Cisco IOS: version 12.3 only; version 12.3(1a) only; version 12.3(2)ja only; version 12.3(2)ja5 only; version 12.3(2)jk only; version 12.3(2)jk1 only; …

Published 2012-09-27. Last modified 2026-06-16.