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CVE-2018-0173

High 8.6 Exploited in the wild (KEV)

Confirmed active exploitation — CISA KEV catalog

Name
Cisco IOS and IOS XE Software Improper Input Validation Vulnerability
Added to catalog
Remediation due date (US federal)
Required action
Apply updates per vendor instructions.

Description

A vulnerability in the Cisco IOS Software and Cisco IOS XE Software function that restores encapsulated option 82 information in DHCP Version 4 (DHCPv4) packets could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a Relay Reply denial of service (DoS) condition. The vulnerability exists because the affected software performs incomplete input validation of encapsulated option 82 information that it receives in DHCPOFFER messages from DHCPv4 servers. An attacker could exploit this vulnerability by sending a crafted DHCPv4 packet to an affected device, which the device would then forward to a DHCPv4 server. When the affected software processes the option 82 information that is encapsulated in the response from the server, an error could occur. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCvg62754.

Metrics

CVSS 3.1
8.6 (HIGH) Score source: NVD CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS — exploit probability
8% (percentile: 95) as of 1 November 2026
CWE
CWE-20

Affected products

cisco: ios; cisco: ios xe; cisco: 4321 integrated services router; cisco: 4331 integrated services router; cisco: 4351 integrated services router; cisco: 4431 integrated services router; cisco: 4451-x integrated services router; cisco: asr 1000 series route processor \(rp2\); cisco: asr 1000 series route processor \(rp3\); cisco: asr 1001-hx; cisco: asr 1001-x; cisco: asr 1002-hx; cisco: asr 1002-x; cisco: cloud services router 1000v; rockwellautomation: allen-bradley armorstratix 5700

References