{"id":"CVE-2026-121286","kind":"vulnerability","aliases":["CVE-2026-121286"],"related":[],"title":"Arista EOS: crafted BGP packets restart routing process, dropping all sessions","description":"On affected platforms running Arista EOS in multi-agent routing model with BGP Segment Routing Traffic Engineering (SR-TE) address family configured, a BGP peer can send crafted BGP packets to cause the BGP process to restart, disrupting all BGP sessions on the device.","summary":"On Arista EOS devices running the multi-agent routing model with the BGP SR-TE address family configured, a BGP peer can send crafted packets that restart the BGP process. The restart disrupts every BGP session on the device.","severity":"medium","cvss":6.5,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["arista-eos","bgp","infrastructure","network-routing"],"not_affected_if":["default-config","no-bgp-sr-te","single-agent-routing"],"how_to_check":"- Check the EOS version with `show version`.\n- Check whether the multi-agent routing model is enabled and whether the BGP SR-TE address family is configured in the running config.","fix":null,"status":"open","published_at":"2026-11-10T20:18:53+00:00","first_seen_at":"2026-11-10T20:46:03+00:00","triaged_at":"2026-11-10T20:48:07+00:00","updated_at":"2026-11-10T20:48:07+00:00","category":"infrastructure","confidence":0.7,"triage":{"at":"2026-11-10T20:48:07Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Arista EOS: crafted BGP packets restart routing process, dropping all sessions","impact":"medium","summary":"On Arista EOS devices running the multi-agent routing model with the BGP SR-TE address family configured, a BGP peer can send crafted packets that restart the BGP process. The restart disrupts every BGP session on the device.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["arista-eos","bgp","network-routing"],"confidence":0.7,"fix_status":"unknown","needs_auth":"unknown","worst_case":"BGP process restarts, dropping all BGP sessions on the device","analyst_note":"Confirm affected EOS version ranges and the fixed release from Arista's security advisory; NVD entry alone gives no fix.","how_to_check":"- Check the EOS version with `show version`.\n- Check whether the multi-agent routing model is enabled and whether the BGP SR-TE address family is configured in the running config.","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["default-config","no-bgp-sr-te","single-agent-routing"],"who_is_affected":"Only Arista EOS devices that run the multi-agent routing model and have the BGP Segment Routing Traffic Engineering address family configured are exposed. The attacker must be a BGP peer that can send packets to the device. Networks without that configuration can skip it.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000722,"input_tokens":4552,"output_tokens":533,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-121286':14A,17A '-2026':13A,16A 'address':43B,88C 'affect':68C 'agent':34B,76C 'arista':1A,19B,27B,71C 'arista-eo':18B 'bgp':4A,21B,39B,47B,56B,62B,80C,92C,97C,102C,108C 'caus':100C 'configur':45B,90C 'craft':3A,51B,96C 'cve':12A,15A 'devic':29B,66B,112C 'disrupt':60B,106C 'drop':9A 'engin':84C 'eo':2A,20B,28B,72C 'everi':61B 'famili':44B,89C 'infrastructur':22B 'model':36B,78C 'multi':33B,75C 'multi-ag':32B,74C 'network':24B 'network-rout':23B 'packet':5A,52B,98C 'peer':48B,93C 'platform':69C 'process':8A,57B,103C 'restart':6A,54B,59B,105C 'rout':7A,25B,35B,77C,82C 'run':30B,70C 'segment':81C 'send':50B,95C 'session':11A,63B,109C 'sr':41B,86C 'sr-te':40B,85C 'te':42B,87C 'traffic':83C","nicknames":[],"mitigations":[],"who_affected":"Only Arista EOS devices that run the multi-agent routing model and have the BGP Segment Routing Traffic Engineering address family configured are exposed. The attacker must be a BGP peer that can send packets to the device. Networks without that configuration can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["aristaeos","bgp","infrastructure","medium","networkrouting"],"campaign_type":null,"search_a":"'-121286':14A,17A '-2026':13A,16A 'arista':1A 'bgp':4A 'craft':3A 'cve':12A,15A 'drop':9A 'eo':2A 'packet':5A 'process':8A 'restart':6A 'rout':7A 'session':11A","search_b":"'address':43B 'agent':34B 'arista':19B,27B 'arista-eo':18B 'bgp':21B,39B,47B,56B,62B 'configur':45B 'craft':51B 'devic':29B,66B 'disrupt':60B 'eo':20B,28B 'everi':61B 'famili':44B 'infrastructur':22B 'model':36B 'multi':33B 'multi-ag':32B 'network':24B 'network-rout':23B 'packet':52B 'peer':48B 'process':57B 'restart':54B,59B 'rout':25B,35B 'run':30B 'send':50B 'session':63B 'sr':41B 'sr-te':40B 'te':42B","search_c":"'address':88C 'affect':68C 'agent':76C 'arista':71C 'bgp':80C,92C,97C,102C,108C 'caus':100C 'configur':90C 'craft':96C 'devic':112C 'disrupt':106C 'engin':84C 'eo':72C 'famili':89C 'model':78C 'multi':75C 'multi-ag':74C 'packet':98C 'peer':93C 'platform':69C 'process':103C 'restart':105C 'rout':77C,82C 'run':70C 'segment':81C 'send':95C 'session':109C 'sr':86C 'sr-te':85C 'te':87C 'traffic':83C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T20:18:53+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/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-2026-121286","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121286","severity":null,"published_at":"2026-11-10T20:18:53+00:00","modified_at":"2026-11-10T20:18:53+00:00","first_seen_at":"2026-11-10T20:46:03+00:00","fetched_at":"2026-11-10T20:46:03+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"}