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

Exploited in the wild High 8.6 Published 28 Mar 2018 Updated 12 Jan 2026

Remote attackers can cause Cisco IOS devices to reload via crafted DHCPv4 packets, resulting in a denial of service.

Exploited in the wild: Since 3 Mar 2022
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2018-0174?

CVE-2018-0174 is a high-severity denial of service vulnerability in Cisco Ios, published on 28 Mar 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-20

Which versions are affected by CVE-2018-0174?

It affects 2 products.

Products include Cisco Ios, Cisco Ios Xe.

How do I fix CVE-2018-0174?

No fix has been published for CVE-2018-0174 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 17 Mar 2022.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2018-0174 being exploited?

Yes. Attackers have exploited CVE-2018-0174 in the wild since at least 3 Mar 2022.

All Cisco Ios vulnerabilities

Sources

Also known as GHSA-qcqh-fmx4-f33r.