Security readout for executives and security teams
Plain-English summary
CVE-2018-0156 can let an unauthenticated remote attacker crash affected Cisco switches that use Smart Install client functionality. The business impact is availability: outages or network instability if exposed devices receive crafted traffic on TCP port 4786.
Executive priority
Treat as high priority because CISA KEV confirms exploitation and the impact is network availability. Focus first on exposed switches supporting critical operations, remote sites, or production connectivity.
Technical view
The flaw is improper packet-data validation in Cisco IOS and IOS XE Smart Install. Network-reachable attackers can trigger a device reload by sending crafted traffic to TCP/4786. The provided record says only Smart Install client switches are affected; Smart Install directors are not.
Likely exposure
Exposure is most likely in Cisco IOS or IOS XE switch environments where Smart Install client functionality is enabled or reachable on TCP/4786. Internet-facing or broadly reachable management networks raise urgency.
Exploitation context
CISA KEV lists this CVE, so active exploitation is supported. The provided sources do not include exploit mechanics, observed targeting details, or exploit tooling, so those points should not be assumed.
Researcher notes
The key exposure condition is Smart Install client status plus TCP/4786 reachability. The source bundle identifies CSCvd40673 and CVSS 7.5, but does not provide fixed-version details or safe detection signatures.
Mitigation direction
- Identify Cisco IOS and IOS XE switches using Smart Install client functionality.
- Follow Cisco’s advisory for affected releases and supported remediation guidance.
- Limit TCP/4786 reachability to trusted management paths where operationally required.
- Prioritize remediation for externally reachable or core network switching devices.
- Track this under CISA KEV-driven vulnerability management deadlines.
Validation and detection
- Inventory Cisco IOS and IOS XE devices and record software versions.
- Check whether each device is a Smart Install client or director.
- Validate TCP/4786 exposure from untrusted and internal network segments.
- Compare device status against Cisco’s advisory and CISA KEV entry.
- Review device history for unexplained reloads or availability incidents.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CWE-399: Exact CWE lookup
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Open ATT&CK lookupCVE-2018-0156 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://ics-cert.us-cert.gov/advisories/ICSA-18-107-04CVE reference · x_refsource_MISC
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-smiCVE reference · x_refsource_CONFIRM
- https://ics-cert.us-cert.gov/advisories/ICSA-18-107-05CVE reference · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-0156CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Resource Management Errors
Resource Management Errors represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.