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CVE-2018-0155

KEVCisco Catalyst Bidirectional Forwarding Detection Denial-of-Service Vulnerability

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.

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.

CVSS 3.1 vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
PublishedMar 28, 2018
Last modifiedJun 17, 2026
Added to KEVMar 3, 2022
Remediation dueMar 17, 2022
    74
    Risk assessment · High

    Actively exploited. Patch immediately.

    Exploitation
    Confirmed in the wild (CISA KEV)
    Federal remediation deadline
    Overdue by 1685 days
    CVSS
    8.6 HIGH
    EPSS (30-day exploit probability)
    7.7% · top 5% of all CVEs
    Weakness
    CWE-388
    Attack vector
    Network, remotely reachable
    Preconditions
    No privileges and no user interaction
    1. 1.Apply updates per vendor instructions.
    2. 2.Treat as emergency change: patch or isolate internet-facing instances first.
    3. 3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
    4. 4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.

    Assessment is derived automatically from the live signals above; verify against your own asset inventory.