{"id":"CVE-2026-121294","kind":"vulnerability","aliases":["CVE-2026-121294"],"related":[],"title":"Arista EOS: crafted S-BFD packet can stop reflector proxy from reflecting","description":"On affected platforms running Arista EOS with a S-BFD reflector proxy configured, an unauthenticated attacker could send a crafted S-BFD Protocol Data Unit (PDU) that might cause the device to temporarily cease reflecting S-BFD packets, potentially resulting in S-BFD session timeouts.","summary":"On Arista EOS devices with an S-BFD reflector proxy configured, a crafted S-BFD packet can make the device temporarily stop reflecting S-BFD packets. The result is S-BFD session timeouts, a disruption of link-liveness checks rather than code execution.","severity":"medium","cvss":6.9,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["arista-eos","network-devices","s-bfd","vendor"],"not_affected_if":["default-config","no-sbfd-reflector-proxy"],"how_to_check":"- Check whether the S-BFD reflector proxy is configured on the Arista EOS device; the sources do not name the exact command.\n- Compare the running EOS version against the affected ranges in the Arista advisory; the sources do not list them.","fix":null,"status":"open","published_at":"2026-11-10T20:18:55+00:00","first_seen_at":"2026-11-10T20:46:04+00:00","triaged_at":"2026-11-10T20:47:59+00:00","updated_at":"2026-11-10T20:47:59+00:00","category":"vendor","confidence":0.6,"triage":{"at":"2026-11-10T20:47:59Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Arista EOS: crafted S-BFD packet can stop reflector proxy from reflecting","impact":"low","summary":"On Arista EOS devices with an S-BFD reflector proxy configured, a crafted S-BFD packet can make the device temporarily stop reflecting S-BFD packets. The result is S-BFD session timeouts, a disruption of link-liveness checks rather than code execution.","audience":"businesses","category":"vendor","nicknames":[],"who_cares":["arista-eos","network-devices","s-bfd"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"Temporary loss of S-BFD reflection, causing session timeouts on the device","analyst_note":"Find the Arista security advisory for CVE-2026-121294 to confirm affected EOS versions, fixed versions and the S-BFD reflector proxy configuration check.","how_to_check":"- Check whether the S-BFD reflector proxy is configured on the Arista EOS device; the sources do not name the exact command.\n- Compare the running EOS version against the affected ranges in the Arista advisory; the sources do not list them.","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["default-config","no-sbfd-reflector-proxy"],"who_is_affected":"Only Arista EOS devices with an S-BFD reflector proxy configured are exposed, according to the sources. Operators running EOS routers or switches without that feature enabled can skip it. The sources do not list affected versions.","user_interaction":"no","product_ecosystem":"vendor","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000752,"input_tokens":4564,"output_tokens":592,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-121294':16A,19A '-2026':15A,18A 'affect':79C 'arista':1A,21B,31B,82C 'arista-eo':20B 'attack':94C 'bfd':6A,28B,38B,46B,57B,64B,88C,101C,117C,124C 'caus':108C 'ceas':113C 'check':73B 'code':76B 'configur':41B,91C 'could':95C 'craft':3A,43B,98C 'cve':14A,17A 'data':103C 'devic':25B,33B,51B,110C 'disrupt':68B 'eo':2A,22B,32B,83C 'execut':77B 'link':71B 'link-liv':70B 'live':72B 'make':49B 'might':107C 'network':24B 'network-devic':23B 'packet':7A,47B,58B,118C 'pdu':105C 'platform':80C 'potenti':119C 'protocol':102C 'proxi':11A,40B,90C 'rather':74B 'reflect':13A,54B,114C 'reflector':10A,39B,89C 'result':60B,120C 'run':81C 's-bfd':4A,26B,36B,44B,55B,62B,86C,99C,115C,122C 'send':96C 'session':65B,125C 'stop':9A,53B 'temporarili':52B,112C 'timeout':66B,126C 'unauthent':93C 'unit':104C 'vendor':29B","nicknames":[],"mitigations":[],"who_affected":"Only Arista EOS devices with an S-BFD reflector proxy configured are exposed, according to the sources. Operators running EOS routers or switches without that feature enabled can skip it. The sources do not list affected versions.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["aristaeos","medium","networkdevices","sbfd","vendor"],"campaign_type":null,"search_a":"'-121294':16A,19A '-2026':15A,18A 'arista':1A 'bfd':6A 'craft':3A 'cve':14A,17A 'eo':2A 'packet':7A 'proxi':11A 'reflect':13A 'reflector':10A 's-bfd':4A 'stop':9A","search_b":"'arista':21B,31B 'arista-eo':20B 'bfd':28B,38B,46B,57B,64B 'check':73B 'code':76B 'configur':41B 'craft':43B 'devic':25B,33B,51B 'disrupt':68B 'eo':22B,32B 'execut':77B 'link':71B 'link-liv':70B 'live':72B 'make':49B 'network':24B 'network-devic':23B 'packet':47B,58B 'proxi':40B 'rather':74B 'reflect':54B 'reflector':39B 'result':60B 's-bfd':26B,36B,44B,55B,62B 'session':65B 'stop':53B 'temporarili':52B 'timeout':66B 'vendor':29B","search_c":"'affect':79C 'arista':82C 'attack':94C 'bfd':88C,101C,117C,124C 'caus':108C 'ceas':113C 'configur':91C 'could':95C 'craft':98C 'data':103C 'devic':110C 'eo':83C 'might':107C 'packet':118C 'pdu':105C 'platform':80C 'potenti':119C 'protocol':102C 'proxi':90C 'reflect':114C 'reflector':89C 'result':120C 'run':81C 's-bfd':86C,99C,115C,122C 'send':96C 'session':125C 'temporarili':112C 'timeout':126C 'unauthent':93C 'unit':104C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T20:18:55+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"psirt@arista.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-121294","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121294","severity":null,"published_at":"2026-11-10T20:18:55+00:00","modified_at":"2026-11-10T20:18:55+00:00","first_seen_at":"2026-11-10T20:46:04+00:00","fetched_at":"2026-11-10T20:46:04+00:00","note":null}],"documents":[],"disclosures":[],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}