CVE-2018-0155
HIGHCISA KEVEPSS 94th pctlDescription
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.
How to fix
Actively exploited, no published fix found yet
CISA required action: Apply updates per vendor instructions.
Federal remediation due: 2022-03-17
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Exploit Intelligence
High risk: more likely to be exploited than 94% of all known CVEs.
Cisco 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.
Apply updates per vendor instructions.
Remediation due: 2022-03-17
References
Related Vulnerabilities
Other CWE-388 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2018-1002105 | Critical | 9.8 | 87% | - | Fix |
| CVE-2016-8745 | High | 7.5 | 16% | - | Fix |
| CVE-2016-9778 | High | 7.5 | 6.8% | - | - |
| CVE-2014-9841 | Critical | 9.8 | 3.9% | - | Fix |
| CVE-2014-9826 | Critical | 9.8 | 3.7% | - | Fix |
| CVE-2017-5401 | Critical | 9.8 | 3.1% | - | Fix |
Common questions
How do I fix CVE-2018-0155?
No published fix for CVE-2018-0155 has been found yet. It is on the CISA Known Exploited Vulnerabilities list; federal agencies must remediate by 2022-03-17. Apply the vendor's mitigations per CISA's guidance.
Is CVE-2018-0155 being actively exploited?
Yes. CVE-2018-0155 is listed in the CISA Known Exploited Vulnerabilities catalog, which means exploitation has been observed in the wild. US federal agencies were required to remediate it by 2022-03-17. Treat it as a priority whatever its CVSS score says.
How severe is CVE-2018-0155?
CVE-2018-0155 has a CVSS v3 base score of 8.6, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-01-13.