CVE-2018-0173
Cisco IOS and IOS XE Software Improper Input Validation Vulnerability
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 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.
- CVSS 3.1
- 8.6 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
- EPSS
- 7.61% probability · 95th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Listed 3 March 2022 · due 17 March 2022
- Weakness
- CWE-20
- Affected
- cisco/ios · cisco/ios xe
- Source
- psirt@cisco.com
EPSS 7.6% 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-2018-0173
References
- http://www.securityfocus.com/bid/103545Broken Link, Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1040591Broken Link, Third Party Advisory, VDB Entry
- https://ics-cert.us-cert.gov/advisories/ICSA-18-107-04Third Party Advisory, US Government Resource
- https://ics-cert.us-cert.gov/advisories/ICSA-18-107-05Third Party Advisory, US Government Resource
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dhcpr2Vendor Advisory
- https://www.tenable.com/security/research/tra-2018-06Third Party Advisory
- http://www.securityfocus.com/bid/103545Broken Link, Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1040591Broken Link, Third Party Advisory, VDB Entry
- https://ics-cert.us-cert.gov/advisories/ICSA-18-107-04Third Party Advisory, US Government Resource
- https://ics-cert.us-cert.gov/advisories/ICSA-18-107-05Third Party Advisory, US Government Resource
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dhcpr2Vendor Advisory
- https://www.tenable.com/security/research/tra-2018-06Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-0173US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.