{"id":"CVE-2026-120981","kind":"vulnerability","aliases":["CVE-2026-120981"],"related":[],"title":"Arista EOS: VPLS-BGP lets a BGP peer churn pseudowire routes","description":"On affected platforms running Arista EOS with VPLS-BGP enabled, an attacker who has established a BGP session with the PE router can affect the route advertisements of VPLS pseudowires, causing a churn of the established routes with other legitimate BGP peers.","summary":"On Arista EOS routers with VPLS-BGP enabled, an attacker who has already set up a BGP session with the provider edge router can change route advertisements for VPLS pseudowires. This causes established routes to churn with other legitimate BGP peers.","severity":"medium","cvss":6.0,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["arista-eos","bgp","infrastructure","network-operators","vpls"],"not_affected_if":["no-untrusted-bgp-peers","vpls-bgp-disabled"],"how_to_check":null,"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":"2026-11-10T20:48:10+00:00","updated_at":"2026-11-10T20:48:10+00:00","category":"infrastructure","confidence":0.5,"triage":{"at":"2026-11-10T20:48:10Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Arista EOS: VPLS-BGP lets a BGP peer churn pseudowire routes","impact":"medium","summary":"On Arista EOS routers with VPLS-BGP enabled, an attacker who has already set up a BGP session with the provider edge router can change route advertisements for VPLS pseudowires. This causes established routes to churn with other legitimate BGP peers.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["arista-eos","vpls","bgp","network-operators"],"confidence":0.5,"fix_status":"unknown","needs_auth":"yes","worst_case":"Established VPLS pseudowire routes churn with other BGP peers","analyst_note":"Check the Arista security advisory for affected EOS versions and the fixed release; sources give no product ranges.","how_to_check":"- unknown","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["vpls-bgp-disabled","no-untrusted-bgp-peers"],"who_is_affected":"Operators running Arista EOS on provider edge routers with VPLS-BGP enabled are affected. An attacker must first establish a BGP session with the PE router, so exposure depends on who can peer with it. Sites without VPLS-BGP, or without untrusted BGP peers, can likely skip it.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000708,"input_tokens":4541,"output_tokens":507,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-120981':15A,18A '-2026':14A,17A 'advertis':55B,97C 'affect':71C,94C 'alreadi':41B 'arista':1A,20B,29B,74C 'arista-eo':19B 'attack':38B,82C 'bgp':5A,8A,22B,35B,45B,68B,79C,87C,111C 'caus':60B,101C 'chang':53B 'churn':10A,64B,103C 'cve':13A,16A 'edg':50B 'enabl':36B,80C 'eo':2A,21B,30B,75C 'establish':61B,85C,106C 'infrastructur':23B 'legitim':67B,110C 'let':6A 'network':25B 'network-oper':24B 'oper':26B 'pe':91C 'peer':9A,69B,112C 'platform':72C 'provid':49B 'pseudowir':11A,58B,100C 'rout':12A,54B,62B,96C,107C 'router':31B,51B,92C 'run':73C 'session':46B,88C 'set':42B 'vpls':4A,27B,34B,57B,78C,99C 'vpls-bgp':3A,33B,77C","nicknames":[],"mitigations":[],"who_affected":"Operators running Arista EOS on provider edge routers with VPLS-BGP enabled are affected. An attacker must first establish a BGP session with the PE router, so exposure depends on who can peer with it. Sites without VPLS-BGP, or without untrusted BGP peers, can likely skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["aristaeos","bgp","infrastructure","medium","networkoperators","vpls"],"campaign_type":null,"search_a":"'-120981':15A,18A '-2026':14A,17A 'arista':1A 'bgp':5A,8A 'churn':10A 'cve':13A,16A 'eo':2A 'let':6A 'peer':9A 'pseudowir':11A 'rout':12A 'vpls':4A 'vpls-bgp':3A","search_b":"'advertis':55B 'alreadi':41B 'arista':20B,29B 'arista-eo':19B 'attack':38B 'bgp':22B,35B,45B,68B 'caus':60B 'chang':53B 'churn':64B 'edg':50B 'enabl':36B 'eo':21B,30B 'establish':61B 'infrastructur':23B 'legitim':67B 'network':25B 'network-oper':24B 'oper':26B 'peer':69B 'provid':49B 'pseudowir':58B 'rout':54B,62B 'router':31B,51B 'session':46B 'set':42B 'vpls':27B,34B,57B 'vpls-bgp':33B","search_c":"'advertis':97C 'affect':71C,94C 'arista':74C 'attack':82C 'bgp':79C,87C,111C 'caus':101C 'churn':103C 'enabl':80C 'eo':75C 'establish':85C,106C 'legitim':110C 'pe':91C 'peer':112C 'platform':72C 'pseudowir':100C 'rout':96C,107C 'router':92C 'run':73C 'session':88C 'vpls':78C,99C 'vpls-bgp':77C","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:L/SA:L/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-2026-120981","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120981","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"}