CVE-2018-0174: Cisco IOS Software and Cisco IOS XE Software Improper Input Validation Vulnerability

High severity, CVSS 8.6. Actively exploited: in CISA KEV since 2022-03-03. EPSS: 7.6% chance of exploitation in the next 30 days.

A vulnerability in the DHCP option 82 encapsulation functionality of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability exists because the affected software performs incomplete input validation of option 82 information that it receives in DHCP Version 4 (DHCPv4) packets from DHCP relay agents. An attacker could exploit this vulnerability by sending a crafted DHCPv4 packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCuh91645.

Affected products

• Cisco IOS: version 12.2(33)sre7a only; up to and including 15.2\(4a\)ea5; up to and including 15.2\(6\)e0a
• Cisco IOS XE: version 12.2(33)sre7a only; up to and including 15.2\(4a\)ea5; up to and including 15.2\(6\)e0a

Published 2018-03-28. Last modified 2026-06-17.