{"id":"CVE-2026-20019","kind":"vulnerability","aliases":["CVE-2026-20019"],"related":[],"title":"Cisco Snort 3: crafted NetFlow packet crashes the detection engine","description":"Multiple Cisco products are affected by a vulnerability in the Snort 3 NetFlow Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection.\r\n\r\nThis vulnerability is due to incomplete error checking when Snort 3 parses UDP Netflow Protocol packets. An attacker could exploit this vulnerability by sending a single crafted Netflow packet through an established connection to be parsed by Snort 3. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a DoS condition.","summary":"Snort 3 in several Cisco products fails to check errors when parsing UDP NetFlow packets. A single crafted NetFlow packet from a remote unauthenticated attacker makes the Snort 3 detection engine restart, interrupting packet inspection.","severity":"medium","cvss":5.8,"epss":0.00416,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["cisco","ids-ips","network-security","snort-3","vendor"],"not_affected_if":["no-snort-3-deployment"],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-10-21T17:18:26+00:00","first_seen_at":"2026-10-23T21:57:29+00:00","triaged_at":"2026-10-25T04:10:05+00:00","updated_at":"2026-10-25T04:10:05+00:00","category":"vendor","confidence":0.6,"triage":{"at":"2026-10-25T04:10:05Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Cisco Snort 3: crafted NetFlow packet crashes the detection engine","impact":"low","summary":"Snort 3 in several Cisco products fails to check errors when parsing UDP NetFlow packets. A single crafted NetFlow packet from a remote unauthenticated attacker makes the Snort 3 detection engine restart, interrupting packet inspection.","category":"vendor","nicknames":[],"who_cares":["cisco","snort-3","network-security","ids-ips"],"confidence":0.6,"needs_auth":"no","worst_case":"Snort 3 detection engine restarts, interrupting packet inspection (denial of service)","analyst_note":"Identify the affected Cisco product list and fixed versions from the Cisco security advisory linked from the NVD entry (https://nvd.nist.gov/vuln/detail/CVE-2026-20019).","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["no-snort-3-deployment"],"who_is_affected":"Organizations running Cisco products that include the Snort 3 detection engine with NetFlow parsing enabled, reachable from the network that sends NetFlow packets. Teams not running affected Cisco products can skip it.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000586,"input_tokens":3489,"output_tokens":474,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-20019':13A,16A '-2026':12A,15A '-3':25B '3':3A,28B,55B,73C,88C,110C,138C,150C 'affect':66C 'allow':79C,143C 'attack':51B,83C,117C,145C 'caus':85C,147C 'check':35B,107C 'cisco':1A,17B,31B,63C 'condit':160C 'connect':132C 'could':78C,118C,142C 'craft':4A,44B,126C 'crash':7A 'cve':11A,14A 'detect':9A,56B,75C,89C,151C 'dos':159C 'due':103C 'engin':10A,57B,76C,90C,152C 'error':36B,106C 'establish':131C 'exploit':119C,141C 'fail':33B 'id':19B 'ids-ip':18B 'incomplet':105C 'inspect':61B,99C 'interrupt':59B,96C 'ip':20B 'make':52B 'multipl':62C 'netflow':5A,40B,45B,74C,113C,127C 'network':22B 'network-secur':21B 'packet':6A,41B,46B,60B,98C,115C,128C 'pars':38B,111C,135C 'product':32B,64C 'protocol':114C 'remot':49B,82C 'restart':58B,92C,154C 'result':93C,156C 'secur':23B 'send':123C 'sever':30B 'singl':43B,125C 'snort':2A,24B,27B,54B,72C,87C,109C,137C,149C 'success':140C 'udp':39B,112C 'unauthent':50B,81C 'unexpect':155C 'vendor':26B 'vulner':69C,101C,121C","nicknames":[],"mitigations":[],"who_affected":"Organizations running Cisco products that include the Snort 3 detection engine with NetFlow parsing enabled, reachable from the network that sends NetFlow packets. Teams not running affected Cisco products can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-21T17:18:26+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L","cvss_by":"psirt@cisco.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-20019","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-20019","severity":null,"published_at":"2026-10-21T17:18:26+00:00","modified_at":"2026-10-22T14:17:39+00:00","first_seen_at":"2026-10-23T21:57:29+00:00","fetched_at":"2026-10-23T22:29:01+00:00","note":null},{"source":"epss","external_id":"CVE-2026-20019","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-20019","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-24T13:15:54+00:00","fetched_at":"2026-10-24T13:15:54+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"}