CVE-2018-0156 Cisco IOS Software and Cisco IOS XE Software Smart Install Denial-of-Service

Exploited in the wild High 7.5 Published 28 Mar 2018 Updated 12 Jan 2026

Unauthenticated remote attackers can cause a denial of service on Cisco IOS devices by sending crafted packets to Smart Install clients.

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-2018-0156?

CVE-2018-0156 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 Smart Install feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to trigger a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to improper validation of packet data. An attacker could exploit this vulnerability by sending a crafted packet to an affected device on TCP port 4786. Only Smart Install client switches are affected. Cisco devices that are configured as a Smart Install director are not affected by this vulnerability. Cisco Bug IDs: CSCvd40673.

Weakness: CWE-20, CWE-399

Which versions are affected by CVE-2018-0156?

It affects 2 products.

Products include Cisco Ios, Cisco Ios Xe.

How do I fix CVE-2018-0156?

No fix has been published for CVE-2018-0156 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-2018-0156 being exploited?

Yes. Attackers have exploited CVE-2018-0156 in the wild since at least 3 Mar 2022.

All Cisco Ios vulnerabilities

Sources

Also known as GHSA-25w3-v3vx-g29w.