---
id: "CVE-2018-0155"
kind: "vulnerability"
aliases: ["CVE-2018-0155"]
title: "Cisco Catalyst 4500 Series Switches and Cisco Catalyst 4500-X Series Switches: Cisco Catalyst Bidirectional Forwarding Detection Denial-of-Service Vulnerability"
severity: "high"
cvss: 8.6
epss: 0.07742
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "Cisco Catalyst 4500 Series Switches and Cisco Catalyst 4500-X Series Switches", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["catalyst-4500", "cisco", "exploited", "infrastructure", "network-switch"]
not_affected_if: ["bfd-offload-disabled", "non-4500-platform"]
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-2018-0155", "first_seen_at": "2026-10-23T19:11:52+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2018-0155", "first_seen_at": "2026-10-23T19:13:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2018-0155", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Cisco Catalyst 4500 Series Switches and Cisco Catalyst 4500-X Series Switches: Cisco Catalyst Bidirectional Forwarding Detection Denial-of-Service Vulnerability

A flaw in the BFD offload code of Cisco Catalyst 4500 and 4500-X switches lets an unauthenticated remote attacker crash the iosd process. The result is a denial of service that takes the switch's routing and forwarding down until it recovers.

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

## Affected

- vendor:Cisco Catalyst 4500 Series Switches and Cisco Catalyst 4500-X Series Switches affected ? fixed ?

## Fix

Apply the update per Cisco's vendor advisory, as CISA requires. Target versions are unknown from these sources.

## Timeline

- 2026-10-23T19:11:52+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2018-0155
- 2026-10-23T19:13:44+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2018-0155
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2018-0155

## From the sources

A vulnerability in the Bidirectional Forwarding Detection (BFD) offload implementation of Cisco Catalyst 4500 Series Switches and Cisco Catalyst 4500-X Series Switches could allow an unauthenticated, remote attacker to cause a crash of the iosd process, causing a denial of service (DoS) condition. The vulnerability is due to insufficient error handling when the BFD header in a BFD packet is incomplete. An attacker could exploit this vulnerability by sending a crafted BFD message to or across an affected switch. A successful exploit could allow the attacker to trigger a reload of the system. This vulnerability affects Catalyst 4500 Supervisor Engine 6-E (K5), Catalyst 4500 Supervisor Engine 6L-E (K10), Catalyst 4500 Supervisor Engine 7-E (K10), Catalyst 4500 Supervisor Engine 7L-E (K10), Catalyst 4500E Supervisor Engine 8-E (K10), Catalyst 4500E Supervisor Engine 8L-E (K10), Catalyst 4500E Supervisor Engine 9-E (K10), Catalyst 4500-X Series Switches (K10), Catalyst 4900M Switch (K5), Catalyst 4948E Ethernet Switch (K5). Cisco Bug IDs: CSCvc40729.

---

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