CVE-2012-4623: Cisco IOS

High severity, CVSS 7.8. EPSS: 2.8% chance of exploitation in the next 30 days.

The DHCPv6 server in Cisco IOS 12.2 through 12.4 and 15.0 through 15.2 and IOS XE 2.1.x through 2.6.x, 3.1.xS before 3.1.4S, 3.1.xSG and 3.2.xSG before 3.2.5SG, 3.2.xS, 3.2.xXO, 3.3.xS, and 3.3.xSG before 3.3.1SG allows remote attackers to cause a denial of service (device reload) via a malformed DHCPv6 packet, aka Bug ID CSCto57723.

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; …
• Cisco IOS XE: version 2.1 only; version 2.1.0 only; version 2.1.1 only; version 2.1.2 only; version 2.2 only; version 2.2.1 only; …

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