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

Source: https://junglewise.ai/threats/cve-2018-0156-cisco-ios-software-and-cisco-ios-xe-software-smart-install-denial  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2022-03-03. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2018-0156 · Severity: critical · CVSS 7.5 · Exploited in the wild · Published 2022-03-03

A vulnerability in the Smart Install feature of Cisco IOS and IOS XE Software allows an unauthenticated, remote attacker to cause a denial-of-service (DoS) condition. The flaw is due to improper validation of packet data sent to TCP port 4786, which can trigger a reload of affected client switches.

Technologies: [Cisco IOS](https://junglewise.ai/threats/technologies/ios), [Cisco Ios Software](https://junglewise.ai/threats/technologies/ios-software), [Cisco IOS XE](https://junglewise.ai/threats/technologies/ios-xe), [Cisco IOS XE Software](https://junglewise.ai/threats/technologies/ios-xe-software). Vendors: [Cisco](https://junglewise.ai/threats/vendors/cisco).

## Quick answers

**Is CVE-2018-0156 exploited in the wild?** Yes. CVE-2018-0156 is known to be exploited in the wild, first recorded on 3 March 2022. Treat it as urgent.

**How severe is CVE-2018-0156?** Critical severity, with a CVSS score of 7.5, published 3 March 2022.

**Which products and versions are affected?** Cisco IOS Software; Cisco IOS XE Software.

**Is there a fix for CVE-2018-0156?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2018-0156 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2018-0156?** Check whether you run Cisco IOS, Cisco Ios Software, Cisco IOS XE or one of the others listed. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Cisco IOS Software
- Cisco IOS XE Software

## Timeline

- 2018-03-28: disclosed: Initial Cisco advisory publication date
- 2022-03-03: kev added: Added to CISA Known Exploited Vulnerabilities Catalog

## Related threats

- [Cisco Snort 3 Detection Engine denial of service in GTP codec](https://junglewise.ai/threats/cve-2026-76445-multiple-cisco-products-are-affected-by-a-vulnerability-in-the)
- [Cisco Snort 3 incorrect calculation vulnerability](https://junglewise.ai/threats/cve-2026-20236-as-part-of-cisco-s-ongoing-commitment-to-proactive-security-and)
- [Cisco Snort 3 GRE detection engine denial of service](https://junglewise.ai/threats/cve-2026-20179-multiple-cisco-products-are-affected-by-a-vulnerability-in-the)
- [Cisco Snort 3 out-of-bounds write](https://junglewise.ai/threats/cve-2026-20043-as-part-of-cisco-s-ongoing-commitment-to-proactive-security-and)
- [Cisco IOS and IOS XE denial of service in XMCP](https://junglewise.ai/threats/cve-2026-20301-cisco-ios-and-ios-xe-denial-of-service-in-xmcp)