{"id":"CVE-2018-0173","published":"2018-03-28T22:29:01Z","modified":"2026-06-17T01:30:00Z","title":"Cisco IOS and IOS XE Software Improper Input Validation Vulnerability","vendor":"Cisco","product":"IOS and IOS XE Software","tier":"core","eol":null,"description":{"text":"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.","provenance":"source","from":"NVD"},"summary":{"text":"The flaw is an improper input validation issue in the DHCPv4 option 82 handling of Cisco IOS and IOS XE Software, specifically in the function that restores encapsulated option 82 information from DHCPOFFER messages received from DHCPv4 servers. An unauthenticated remote attacker who can send a crafted DHCPv4 packet to an affected device, which then gets forwarded to a DHCPv4 server, can trigger an error in processing the server's response and cause the device to reload, producing a Relay Reply denial of service, with no authentication or user interaction required.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:13:22Z"},"cvss":{"score":8.6,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.07608,"percentile":0.9453,"date":"2026-10-28","provenance":"source"},"kev":{"dateAdded":"2022-03-03","dueDate":"2022-03-17","ransomware":false,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2018-0173","provenance":"source"},"vulncheckKev":{"dateAdded":"2022-03-03","exploitedFirstSeen":"2022-03-03","ransomware":false,"evidence":[{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2022-03-03"},{"url":"https://www.cisco.com/c/en/us/support/docs/csa/cisco-sa-20180328-dhcpr2.html","date":"2022-12-15"}],"evidenceTotal":2,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"},{"name":"Actively_Exploited_Kev | Oct 20, 2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"},{"name":"Actively_Exploited_Kev | Oct 18, 2026","url":"https://otx.alienvault.com/pulse/6ad38c22e1848f8189d1c121","created":"2026-10-17"}],"provenance":"machine"},"cwes":[{"id":"CWE-20","name":"Improper Input Validation"}],"references":[{"url":"http://www.securityfocus.com/bid/103545","tags":["Broken Link","Third Party Advisory","VDB Entry"]},{"url":"http://www.securitytracker.com/id/1040591","tags":["Broken Link","Third Party Advisory","VDB Entry"]},{"url":"https://ics-cert.us-cert.gov/advisories/ICSA-18-107-04","tags":["Third Party Advisory","US Government Resource"]},{"url":"https://ics-cert.us-cert.gov/advisories/ICSA-18-107-05","tags":["Third Party Advisory","US Government Resource"]},{"url":"https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dhcpr2","tags":["Vendor Advisory"]},{"url":"https://www.tenable.com/security/research/tra-2018-06","tags":["Third Party Advisory"]},{"url":"http://www.securityfocus.com/bid/103545","tags":["Broken Link","Third Party Advisory","VDB Entry"]},{"url":"http://www.securitytracker.com/id/1040591","tags":["Broken Link","Third Party Advisory","VDB Entry"]},{"url":"https://ics-cert.us-cert.gov/advisories/ICSA-18-107-04","tags":["Third Party Advisory","US Government Resource"]},{"url":"https://ics-cert.us-cert.gov/advisories/ICSA-18-107-05","tags":["Third Party Advisory","US Government Resource"]},{"url":"https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dhcpr2","tags":["Vendor Advisory"]},{"url":"https://www.tenable.com/security/research/tra-2018-06","tags":["Third Party Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-0173","tags":["US Government Resource"]}],"techniques":[{"id":"T1190","name":"Exploit Public-Facing Application","tactics":["initial-access"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Remote crafted packet targets exposed network service","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"An attacker could exploit this vulnerability by sending a crafted DHCPv4 packet to an affected device","start":500,"end":601}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1499.004","name":"Application or System Exploitation","tactics":["impact"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Device reload causes application or OS denial of service","mappingType":"primary_impact","evidence":[{"from":"description","quote":"cause the affected device to reload, resulting in a DoS condition","start":847,"end":912}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2018-0996","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2018-0996","exploited":true,"exploitedSince":"2022-03-03","provenance":"source"},"exploits":[],"exploitSources":null,"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1190"],"provenance":"ai"},{"stage":"primary","techniques":["T1499.004"],"provenance":"ai"}],"timeline":[{"date":"2018-03-28","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2018-0173","provenance":"source"},{"date":"2022-03-03","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","provenance":"source"},{"date":"2022-03-03","kind":"kev","label":"Added to CISA KEV","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2022-03-03","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2018-0996","provenance":"source"}],"speed":{"daysToPublicExploit":null,"firstExploitFrom":null,"daysToKev":1436},"priority":{"score":62.9,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck KEV"},{"name":"Recent KEV listing","points":0.0,"detail":"added 1701 days ago"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":18.91,"detail":"percentile 0.9453"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":0.0,"detail":"none found"},{"name":"Mentioned in OTX pulses","points":3.0,"detail":"50 pulses"},{"name":"CVSS severity","points":6.02,"detail":"base score 8.6"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]},"lineage":{"familyId":"fam-class-cisco-ios-and-ios-xe-cwe-20"}}