{"id":"CVE-2026-20218","kind":"vulnerability","aliases":["CVE-2026-20218"],"related":[],"title":"Cisco Snort 3: crafted VBA data crashes the detection engine","description":"A vulnerability in the Snort 3 Visual Basic for Applications (VBA) Decompression Engine of multiple Cisco products could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS) condition.  \r\n\r\nThis vulnerability is due to improper range checking when Snort 3 decompresses VBA data, which is user controlled. An attacker could exploit this vulnerability by sending crafted VBA data to the Snort 3 Detection Engine of a targeted device. A successful exploit could allow the attacker to cause an overflow of stack data, which could result in a DoS condition.","summary":"Snort 3's VBA decompression engine in multiple Cisco products does not check ranges properly when decompressing user-controlled VBA data. A remote, unauthenticated attacker can send crafted traffic that restarts the Snort 3 Detection Engine, causing denial of service.","severity":"medium","cvss":5.8,"epss":0.00416,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["cisco","infrastructure","network-security","snort-3"],"not_affected_if":["no-snort-3"],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-10-21T17:18:27+00:00","first_seen_at":"2026-10-23T21:57:29+00:00","triaged_at":"2026-10-25T04:10:02+00:00","updated_at":"2026-10-25T04:10:02+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-25T04:10:02Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Cisco Snort 3: crafted VBA data crashes the detection engine","impact":"low","summary":"Snort 3's VBA decompression engine in multiple Cisco products does not check ranges properly when decompressing user-controlled VBA data. A remote, unauthenticated attacker can send crafted traffic that restarts the Snort 3 Detection Engine, causing denial of service.","category":"infrastructure","nicknames":[],"who_cares":["cisco","snort-3","network-security"],"confidence":0.6,"needs_auth":"no","worst_case":"Snort 3 detection engine restarts, causing denial of service","analyst_note":"Find the affected Cisco products and fixed versions in the Cisco security advisory for CVE-2026-20218, and confirm whether VBA decompression is on by default.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["no-snort-3"],"who_is_affected":"Cisco products that ship the Snort 3 detection engine with VBA decompression enabled are affected; the sources do not list the specific products or versions. Teams not running Cisco devices with Snort 3 can skip it.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000574,"input_tokens":3501,"output_tokens":447,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-20218':13A,16A '-2026':12A,15A '-3':23B '3':3A,25B,58B,70C,92C,116C,138C 'allow':83C,149C 'applic':74C 'attack':49B,87C,125C,151C 'basic':72C 'caus':61B,89C,153C 'check':36B,113C 'cisco':1A,17B,32B,80C 'condit':105C,165C 'control':43B,123C 'could':82C,126C,148C,160C 'craft':4A,52B,132C 'crash':7A 'cve':11A,14A 'data':6A,45B,119C,134C,158C 'decompress':28B,40B,76C,117C 'denial':62B,101C 'detect':9A,59B,93C,139C 'devic':144C 'dos':104C,164C 'due':109C 'engin':10A,29B,60B,77C,94C,140C 'exploit':127C,147C 'improp':111C 'infrastructur':18B 'multipl':31B,79C 'network':20B 'network-secur':19B 'overflow':155C 'product':33B,81C 'proper':38B 'rang':37B,112C 'remot':47B,86C 'restart':55B,96C 'result':98C,161C 'secur':21B 'send':51B,131C 'servic':64B,103C 'snort':2A,22B,24B,57B,69C,91C,115C,137C 'stack':157C 'success':146C 'target':143C 'traffic':53B 'unauthent':48B,85C 'unexpect':97C 'user':42B,122C 'user-control':41B 'vba':5A,27B,44B,75C,118C,133C 'visual':71C 'vulner':66C,107C,129C","nicknames":[],"mitigations":[],"who_affected":"Cisco products that ship the Snort 3 detection engine with VBA decompression enabled are affected; the sources do not list the specific products or versions. Teams not running Cisco devices with Snort 3 can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-21T17:18:27+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-2026-20218","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-20218","severity":null,"published_at":"2026-10-21T17:18:27+00:00","modified_at":"2026-10-22T19:17:51+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-2026-20218","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-20218","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"}