---
id: "CVE-2018-0156"
kind: "vulnerability"
aliases: ["CVE-2018-0156"]
title: "Cisco IOS Software and Cisco IOS XE Software: Cisco IOS Software and Cisco IOS XE Software Smart Install Denial-of-Service Vulnerability"
severity: "high"
cvss: 7.8
epss: 0.0936
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "Cisco IOS Software and Cisco IOS XE Software", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["cisco", "exploited", "infrastructure", "ios", "ios-xe", "network-gear"]
not_affected_if: ["non-cisco-devices", "smart-install-disabled"]
published_at: "2018-03-28T22:29:00+00:00"
first_seen_at: "2026-10-23T19:11:52+00:00"
updated_at: "2026-10-23T21:57:35+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2018-0156", "first_seen_at": "2026-10-23T19:11:52+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2018-0156", "first_seen_at": "2026-10-23T19:13:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2018-0156", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Cisco IOS Software and Cisco IOS XE Software: Cisco IOS Software and Cisco IOS XE Software Smart Install Denial-of-Service Vulnerability

Cisco IOS and IOS XE switches and routers with the Smart Install feature enabled can be forced to reload by an unauthenticated remote attacker. The result is a denial of service, and CISA lists this CVE as actively exploited.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Cisco IOS Software and Cisco IOS XE Software affected ? fixed ?

## Fix

Apply the vendor updates per Cisco's advisory; the sources do not name the fixed versions.
Disable Smart Install if it is not needed; the sources do not give the exact command.

## Timeline

- 2026-10-23T19:11:52+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2018-0156
- 2026-10-23T19:13:44+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2018-0156
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2018-0156

## From the sources

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.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_