CVEs / CVE-2018-0156

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

Known exploited in the CISA KEV catalog since 3 Mar 2022
high 7.5 CVSS 3.1 (NVD)
EPSS 9.36% chance of exploitation in the next 30 days, higher than 95% of CVEs (30 Oct 2026)
Last changed at its sources 17 Jun 2026

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Summary

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.
CISA, Known Exploited Vulnerabilities catalog

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.
The CVE record, via NVD · published 28 Mar 2018 · NVD status: Analyzed

Affected and fixed versions

As stated by the CVE record (from the CNA)
Product	Affected	Fixed in
n/a Cisco IOS and IOS XE	Cisco IOS and IOS XE	—

Exploitation

In CISA KEV since	3 Mar 2022
Due date for US federal agencies	17 Mar 2022
Used in ransomware campaigns	Unknown
Required action	Apply updates per vendor instructions.

Severity

CVSS 3.1	7.5 high `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` Scored by NVD
Weakness	CWE-399, CWE-20

References

CVE-2018-0156 on NVD
CVE-2018-0156 in the CISA KEV catalog
http://www.securityfocus.com/bid/103569 Third Party Advisory, VDB Entry
http://www.securitytracker.com/id/1040596 Third Party Advisory, VDB Entry
https://ics-cert.us-cert.gov/advisories/ICSA-18-107-04 Third Party Advisory, US Government Resource
https://ics-cert.us-cert.gov/advisories/ICSA-18-107-05 Third Party Advisory, US Government Resource
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-smi Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-0156 US Government Resource

Sources

Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.

This product uses data from the NVD API but is not endorsed or certified by the NVD.