Security readout for executives and security teams
Plain-English summary
CVE-2018-0173 can let an unauthenticated remote attacker crash affected Cisco IOS and IOS XE devices by triggering faulty DHCPv4 option 82 handling. The business impact is availability: network devices may reload, disrupting routing or access services.
Executive priority
Treat this as a high-priority availability risk for Cisco network infrastructure. KEV status raises urgency, but remediation should follow Cisco guidance because the provided bundle does not include exact fixed versions.
Technical view
The flaw is incomplete input validation in Cisco IOS and IOS XE DHCPv4 relay handling when restoring encapsulated option 82 data from DHCPOFFER responses. A successful exploit can cause the affected device to reload, producing a Relay Reply denial-of-service condition.
Likely exposure
Exposure is most likely where Cisco IOS or IOS XE devices process DHCPv4 relay traffic involving option 82. The bundle does not identify specific versions, configurations, or platforms beyond Cisco IOS and IOS XE.
Exploitation context
CISA KEV inclusion indicates this CVE is known to be exploited. The provided sources do not include campaign details, exploit maturity, affected version ranges, or evidence of current targeting.
Researcher notes
The key weakness is CWE-20 input validation in DHCPv4 option 82 relay processing. Analysis should focus on device role, DHCP relay exposure, and reload evidence, without assuming impact beyond denial of service.
Mitigation direction
- Review Cisco’s advisory for affected releases and vendor-approved fixed software.
- Prioritize internet-edge, branch, campus, and industrial networks using Cisco IOS or IOS XE DHCP relay.
- Restrict untrusted DHCPv4 paths where operationally feasible until vendor guidance is applied.
- Monitor affected devices for unexpected reloads and DHCP-related denial-of-service symptoms.
Validation and detection
- Inventory Cisco IOS and IOS XE devices performing DHCPv4 relay functions.
- Compare software releases and configuration exposure against Cisco’s advisory.
- Review device logs for unexpected reloads around DHCPv4 relay activity.
- Confirm whether DHCP option 82 handling is enabled or present in relevant traffic paths.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-20: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2018-0173 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
- 8.6 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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:C/C:N/I:N/A:H3.94Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.6HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dhcpr2CVE reference · x_refsource_CONFIRM
- https://ics-cert.us-cert.gov/advisories/ICSA-18-107-04CVE reference · x_refsource_MISC
- https://www.tenable.com/security/research/tra-2018-06CVE reference · x_refsource_MISC
- 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-2018-0173CVE 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.
Improper Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.