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UK Cyber Defence
VulnerabilityAnalyzed

CVE-2018-0156

Cisco IOS Software and Cisco IOS XE Software Smart Install Denial-of-Service Vulnerability

KEVHIGH 7.5EPSS 9.36%

Does this matter?

Known to be exploited in the wild (CISA KEV, CISA remediation deadline 17 March 2022). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.

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.

CVSS 3.1
7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
9.36% probability · 95th percentile
Public exploits
None in Exploit-DB
CISA KEV
Listed 3 March 2022 · due 17 March 2022
Weakness
CWE-399, CWE-20
Affected
cisco/ios · cisco/ios xe
Source
psirt@cisco.com
EPSS trend
0%5%10%27 October 2026: 9.36%27 October 202627 October 2026

EPSS 9.4% since 27 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

CISA notes

Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2018-0156

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.