CVE-2018-0156

Exp

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.

Published: 2018-03-28 Last update: 2026-01-13 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-0156 is rated Critical Active Threat (91.5/100): CVSS High severity, with high exploitation likelihood (EPSS 15.53%, 95th percentile). CISA KEV confirms active exploitation (added 2022-03-03) affecting Cisco / IOS Software and Cisco IOS XE Software. a weakness (CWE-20) Unauthenticated remote administrative access may be possible. EPSS rose +3.42% over the last day, indicating growing attacker interest. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2018-0156

Name: Cisco IOS Software and Cisco IOS XE Software Smart Install Denial-of-Service Vulnerability · CISA KEV detail

Exploit added: 2022-03-03

Action due: 2022-03-17

Required action: Apply updates per vendor instructions.

Exploit prediction scoring system (EPSS) score for CVE-2018-0156

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-07 12.11% 15.53% +3.42%
2 2026-01-17 9.70% 12.11% +2.41%
3 2025-12-16 — 9.70% —

Full EPSS history (18 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-0156

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0
7.8 2.0 HIGH
AV:N/AC:L/Au:N/C:N/I:N/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:C)
Complete availability impact.
 10.0 6.9 [email protected]

Weakness enumeration for CVE-2018-0156

Affected software / configurations for CVE-2018-0156

Vendor Product Version Raw CPE
cisco ios 15.2\(2\)e4 cpe:2.3:o:cisco:ios:15.2\(2\)e4:*:*:*:*:*:*:*
cisco ios 15.2\(2a\)ja cpe:2.3:o:cisco:ios:15.2\(2a\)ja:*:*:*:*:*:*:*
cisco ios_xe 15.2\(2\)e4 cpe:2.3:o:cisco:ios_xe:15.2\(2\)e4:*:*:*:*:*:*:*
cisco ios_xe 15.2\(2a\)ja cpe:2.3:o:cisco:ios_xe:15.2\(2a\)ja:*:*:*:*:*:*:*

References for CVE-2018-0156

cvelogic Threat Intelligence