{"id":"CVE-2026-120982","kind":"vulnerability","aliases":["CVE-2026-120982"],"related":[],"title":"Arista EOS: crafted BGP messages force repeated session resets, disrupting routing","description":"On affected platforms running Arista EOS with Border Gateway Protocol (BGP) configured, An unauthenticated attacker who can establish a BGP peering session with an affected device and can send specially crafted BGP messages to cause repeated BGP session resets, enabling sustained disruption to network routing and traffic forwarding.","summary":"On Arista EOS devices with BGP configured, an unauthenticated attacker who can establish a BGP peering session can send crafted BGP messages. These cause repeated BGP session resets, which disrupts routing and traffic forwarding.","severity":"high","cvss":8.7,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"Arista EOS","fixed":["4.37.0F","4.36.3M","4.35.7M","4.34.9M","4.33.11M"],"affected":"<= 4.36.2F (4.36.x), <= 4.35.6M (4.35.x), <= 4.34.8M (4.34.x), <= 4.33.10M (4.33.x), all End of Support trains","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["arista-eos","bgp","infrastructure","network-operators"],"not_affected_if":["no-bgp-configured","peering-restricted-to-trusted-peers","routing-model-ribd"],"how_to_check":"Exposed only if BGP is configured AND the multi-agent routing model is in use. Run 'show ip bgp summary' (\"% BGP is not active\" means not exposed) and 'show running-config all | inc service routing protocols' (\"model ribd\" means not exposed; \"model multi-agent\" plus BGP means exposed if the version is affected). Then 'show version' and compare to affected: 4.36.2F and below, 4.35.6M and below, 4.34.8M and below, 4.33.10M and below, and all End of Support trains. Look for log signs: show logging | grep \"NOTIFICATION.*UPDATE Message Error\".","fix":"Upgrade EOS to 4.37.0F, 4.36.3M, 4.35.7M, 4.34.9M or 4.33.11M or later in your train. No hotfix. Workaround: under router bgp, 'neighbor default received attribute discard 22' (re-enabling attribute 22 on any peer restores exposure); or use TCP-AO peer authentication.","status":"open","published_at":"2026-11-10T20:18:53+00:00","first_seen_at":"2026-11-10T20:46:03+00:00","triaged_at":"2026-11-10T20:47:26+00:00","updated_at":"2026-11-10T20:58:28+00:00","category":"infrastructure","confidence":0.9,"triage":{"at":"2026-11-10T20:47:26Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Arista EOS: crafted BGP messages force repeated session resets, disrupting routing","impact":"medium","summary":"On Arista EOS devices with BGP configured, an unauthenticated attacker who can establish a BGP peering session can send crafted BGP messages. These cause repeated BGP session resets, which disrupts routing and traffic forwarding.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["arista-eos","bgp","network-operators"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"repeated BGP session resets disrupt routing and traffic forwarding","analyst_note":"Find the Arista security advisory and confirm affected and fixed EOS versions and any workaround from the NVD entry's references.","how_to_check":"- Check whether BGP is configured on Arista EOS devices, for example with `show running-config | include router bgp`\n- Check the running EOS version with `show version`, then compare it to the fixed versions in the vendor advisory (unknown from these sources)","plain_action":"","product_name":"Arista EOS","needs_analyst":true,"not_affected_if":["no-bgp-configured","peering-restricted-to-trusted-peers"],"who_is_affected":"Only Arista EOS devices that run BGP are affected, and the attacker must be able to establish a BGP peering session with the device. Networks that do not expose BGP peering to untrusted parties are less exposed. The sources do not list affected EOS versions.","user_interaction":"no","product_ecosystem":"vendor","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000749,"input_tokens":4564,"output_tokens":585,"severity_before":"high"},"analyst_status":"done","analyst_note":"Find the Arista security advisory and confirm affected and fixed EOS versions and any workaround from the NVD entry's references.","search":"'-120982':14A,17A '-2026':13A,16A 'affect':63C,86C 'arista':1A,18A,21B,29B,66C 'arista-eo':20B 'attack':37B,76C 'bgp':4A,23B,33B,42B,48B,53B,72C,81C,93C,98C 'border':69C 'caus':51B,96C 'configur':34B,73C 'craft':3A,47B,92C 'cve':12A,15A 'devic':31B,87C 'disrupt':10A,57B,103C 'enabl':101C 'eo':2A,22B,30B,67C 'eos':19A 'establish':40B,79C 'forc':6A 'forward':61B,109C 'gateway':70C 'infrastructur':24B 'messag':5A,49B,94C 'network':26B,105C 'network-oper':25B 'oper':27B 'peer':43B,82C 'platform':64C 'protocol':71C 'repeat':7A,52B,97C 'reset':9A,55B,100C 'rout':11A,58B,106C 'run':65C 'send':46B,90C 'session':8A,44B,54B,83C,99C 'special':91C 'sustain':102C 'traffic':60B,108C 'unauthent':36B,75C","nicknames":[],"mitigations":[],"who_affected":"Arista EOS switches and routers (7000-series, CloudEOS, cEOS-lab, vEOS-lab, CloudVision eXchange) that run BGP with the multi-agent routing protocol model and a release listed as affected. A peer that can establish a BGP session can send crafted messages that repeatedly reset it. You can skip it if BGP is not configured, the device uses the ribd model, or it is a Wi-Fi AP, CloudVision Portal, DMF, NetVisor or VeloCloud product; Arista lists those as not affected.","tier":"B","verified":{"fix":{"at":"2026-11-10T20:58:28Z","by":"analyst","doc":"https://www.arista.com/en/support/advisories-notices/security-advisory/25029-security-advisory-0207","run_id":2733},"products":{"at":"2026-11-10T20:58:28Z","by":"analyst","doc":"https://www.arista.com/en/support/advisories-notices/security-advisory/25029-security-advisory-0207","run_id":2733},"mitigations":{"at":"2026-11-10T20:58:28Z","by":"analyst","doc":"https://www.arista.com/en/support/advisories-notices/security-advisory/25029-security-advisory-0207","run_id":2733},"workarounds":{"at":"2026-11-10T20:58:28Z","by":"analyst","doc":"https://www.arista.com/en/support/advisories-notices/security-advisory/25029-security-advisory-0207","run_id":2733},"how_to_check":{"at":"2026-11-10T20:58:28Z","by":"analyst","doc":"https://www.arista.com/en/support/advisories-notices/security-advisory/25029-security-advisory-0207","run_id":2733},"who_affected":{"at":"2026-11-10T20:58:28Z","by":"analyst","doc":"https://www.arista.com/en/support/advisories-notices/security-advisory/25029-security-advisory-0207","run_id":2733}},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":["aristaeos","eos"],"ptokens":["arista","eos"],"labels":["aristaeos","bgp","high","infrastructure","networkoperators","vendor"],"campaign_type":null,"search_a":"'-120982':14A,17A '-2026':13A,16A 'arista':1A,18A 'bgp':4A 'craft':3A 'cve':12A,15A 'disrupt':10A 'eo':2A 'eos':19A 'forc':6A 'messag':5A 'repeat':7A 'reset':9A 'rout':11A 'session':8A","search_b":"'arista':21B,29B 'arista-eo':20B 'attack':37B 'bgp':23B,33B,42B,48B,53B 'caus':51B 'configur':34B 'craft':47B 'devic':31B 'disrupt':57B 'eo':22B,30B 'establish':40B 'forward':61B 'infrastructur':24B 'messag':49B 'network':26B 'network-oper':25B 'oper':27B 'peer':43B 'repeat':52B 'reset':55B 'rout':58B 'send':46B 'session':44B,54B 'traffic':60B 'unauthent':36B","search_c":"'affect':63C,86C 'arista':66C 'attack':76C 'bgp':72C,81C,93C,98C 'border':69C 'caus':96C 'configur':73C 'craft':92C 'devic':87C 'disrupt':103C 'enabl':101C 'eo':67C 'establish':79C 'forward':109C 'gateway':70C 'messag':94C 'network':105C 'peer':82C 'platform':64C 'protocol':71C 'repeat':97C 'reset':100C 'rout':106C 'run':65C 'send':90C 'session':83C,99C 'special':91C 'sustain':102C 'traffic':108C 'unauthent':75C","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:N/PR:N/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-2026-120982","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120982","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},{"source":"analyst","external_id":"CVE-2026-120982:2733","url":"https://www.arista.com/en/support/advisories-notices/security-advisory/25029-security-advisory-0207","severity":null,"published_at":"2026-11-10T20:58:28+00:00","modified_at":"2026-11-10T20:58:28+00:00","first_seen_at":"2026-11-10T20:58:28+00:00","fetched_at":"2026-11-10T20:58:28+00:00","note":"Read Arista SA 0207 (primary): affected/fixed versions, multi-agent condition, workaround all from the vendor page. Not exploited per Arista; no PoC checked; social not searched (published today).","cites":["https://www.arista.com/en/support/advisories-notices/security-advisory/25029-security-advisory-0207"]}],"documents":[{"id":118464,"url":"https://www.arista.com/en/support/advisories-notices/security-advisory/25029-security-advisory-0207","title":"Arista Security Advisory 0207 (CVE-2026-120982)","kind":"advisory","source":"analyst","publisher":null,"text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null}],"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"}