{"id":"CVE-2018-0156","kind":"vulnerability","aliases":["CVE-2018-0156"],"related":[],"title":"Cisco IOS Software and Cisco IOS XE Software: Cisco IOS Software and Cisco IOS XE Software Smart Install Denial-of-Service Vulnerability","description":"A vulnerability in the Smart Install feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to trigger a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to improper validation of packet data. An attacker could exploit this vulnerability by sending a crafted packet to an affected device on TCP port 4786. Only Smart Install client switches are affected. Cisco devices that are configured as a Smart Install director are not affected by this vulnerability. Cisco Bug IDs: CSCvd40673.","summary":"Cisco IOS and IOS XE switches and routers with the Smart Install feature enabled can be forced to reload by an unauthenticated remote attacker. The result is a denial of service, and CISA lists this CVE as actively exploited.","severity":"high","cvss":7.8,"epss":0.0936,"exploited":true,"exploited_at":"2022-03-03T00:00:00+00:00","products":[{"name":"Cisco IOS Software and Cisco IOS XE Software","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["cisco","exploited","infrastructure","ios","ios-xe","network-gear"],"not_affected_if":["non-cisco-devices","smart-install-disabled"],"how_to_check":null,"fix":"Apply the vendor updates per Cisco's advisory; the sources do not name the fixed versions.\nDisable Smart Install if it is not needed; the sources do not give the exact command.","status":"open","published_at":"2018-03-28T22:29:00+00:00","first_seen_at":"2026-10-23T19:11:52+00:00","triaged_at":"2026-10-23T21:24:15+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T21:24:15Z","model":"claude-haiku-5-5","output":{"fix":"Apply the vendor updates per Cisco's advisory; the sources do not name the fixed versions.\nDisable Smart Install if it is not needed; the sources do not give the exact command.","reach":"network","impact":"low","summary":"Cisco IOS and IOS XE switches and routers with the Smart Install feature enabled can be forced to reload by an unauthenticated remote attacker. The result is a denial of service, and CISA lists this CVE as actively exploited.","category":"infrastructure","who_cares":["cisco","ios","ios-xe","network-gear"],"confidence":0.6,"needs_auth":"no","worst_case":"Attacker reloads the device, causing a network denial of service","analyst_note":"Find the fixed IOS and IOS XE versions and the command to check or disable Smart Install in the Cisco advisory linked from the KEV entry.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["smart-install-disabled","non-cisco-devices"],"user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"high"},"cost_usd":0.000481,"input_tokens":2907,"output_tokens":380,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-0156':26A,29A '-2018':25A,28A '4786':153C 'activ':85B 'affect':115C,148C,160C,173C 'allow':104C 'and':33A 'attack':71B,108C,136C 'bug':178C 'cisa':80B 'cisco':1A,5A,9A,13A,30A,34A,38B,48B,95C,99C,161C,177C 'client':157C 'condit':124C 'configur':165C 'could':103C,137C 'craft':144C 'cscvd40673':180C 'cve':24A,27A,83B 'data':134C 'denial':20A,76B,120C 'denial-of-servic':19A 'devic':116C,149C,162C 'director':170C 'dos':123C 'due':128C 'enabl':61B 'exploit':39B,86B,138C 'featur':60B,93C 'forc':64B 'gear':47B 'id':179C 'improp':130C 'infrastructur':40B 'instal':18A,59B,92C,156C,169C 'io':2A,6A,10A,14A,41B,43B,49B,51B,96C,100C 'ios':31A,35A 'ios-x':42B 'list':81B 'network':46B 'network-gear':45B 'packet':133C,145C 'port':152C 'reload':66B,112C 'remot':70B,107C 'result':73B,117C 'router':55B 'send':142C 'servic':22A,78B,122C 'smart':17A,58B,91C,155C,168C 'softwar':3A,8A,11A,16A,97C,102C 'software':32A,37A 'switch':53B,158C 'tcp':151C 'trigger':110C 'unauthent':69B,106C 'valid':131C 'vulner':23A,88C,126C,140C,176C 'xe':7A,15A,36A,44B,52B,101C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2018-03-28T22:29:00+00:00","kev":{"dateAdded":"2022-03-03","dueDate":"2022-03-17","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2018-0156","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2018-0156","severity":null,"published_at":"2022-03-03T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:52+00:00","fetched_at":"2026-10-25T14:39:40+00:00","note":null},{"source":"epss","external_id":"CVE-2018-0156","url":"https://api.first.org/data/v1/epss?cve=CVE-2018-0156","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:44+00:00","fetched_at":"2026-10-23T19:13:44+00:00","note":null},{"source":"nvd","external_id":"CVE-2018-0156","url":"https://nvd.nist.gov/vuln/detail/CVE-2018-0156","severity":null,"published_at":"2018-03-28T22:29:00+00:00","modified_at":"2026-06-17T01:29:57+00:00","first_seen_at":"2026-10-23T21:57:35+00:00","fetched_at":"2026-10-23T21:57:35+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}