VulnTideExploited vulnerabilities, by vendor. Data as of .
Known exploitedIn CISA's KEV catalog since Ransomware use: unknown
Cisco IOS and IOS XE Software

CVE-2018-0173: Cisco IOS and IOS XE Software Improper Input Validation Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on , 1,436 days after the CVE record was published.

How likely is exploitation in the next 30 days?
7.6%

EPSS score, percentile 94.5 of all scored records

How severe?
8.6 High

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

CISA deadline . Apply updates per vendor instructions.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

  • Cisco IOS and IOS XE

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

What to do

Required action, set by CISA

Apply updates per vendor instructions.

CISA due date for this action: .

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

Affected products and versions

As listed in the CVE record.

n/a Cisco IOS and IOS XE
StatusVersions
AffectedCisco IOS and IOS XE

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

About this vulnerability

A vulnerability in the Cisco IOS Software and Cisco IOS XE Software function that restores encapsulated option 82 information in DHCP Version 4 (DHCPv4) packets can allow for denial-of-service (DoS).

Summary: CISA's KEV catalog, as of .

  • CISA added CVE-2018-0173 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Mar 2022.
  • CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
  • The due date CISA sets for the required action is 17 Mar 2022.
  • The CVE record was published on 28 Mar 2018, 1,436 days before it was added to KEV.
  • The CVE record carries a CVSS v3.1 base score of 8.6 (High), taken from CISA's enrichment of the record.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 7.6% (percentile 94.5), as of 28 Oct 2026.
  • CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.

Description

A vulnerability in the Cisco IOS Software and Cisco IOS XE Software function that restores encapsulated option 82 information in DHCP Version 4 (DHCPv4) packets could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a Relay Reply denial of service (DoS) condition. The vulnerability exists because the affected software performs incomplete input validation of encapsulated option 82 information that it receives in DHCPOFFER messages from DHCPv4 servers. An attacker could exploit this vulnerability by sending a crafted DHCPv4 packet to an affected device, which the device would then forward to a DHCPv4 server. When the affected software processes the option 82 information that is encapsulated in the response from the server, an error could occur. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCvg62754.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

Weakness

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

DateEvent
CVE record published
Added to CISA KEV
CISA due date for the required action
CVE record last updated

References

More exploited Cisco vulnerabilities

  • CVE-2026-76519: Cisco Secure Email Gateway Relative Path Traversal Vulnerability (added )
  • CVE-2026-76504: Cisco Catalyst SD-WAN Manager Hex Encoding Vulnerability (added )
  • CVE-2026-76460: Cisco Identity Services Engine Incorrect Use of Privileged APIs Vulnerability (added )
  • CVE-2026-76461: Cisco Secure Email Gateway SQL Injection Vulnerability (added )
  • CVE-2026-20079: Cisco Firewall Management Center Authentication Bypass Using an Alternate Path or Channel Vulnerability (added )
  • CVE-2026-20349: Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability (added )