{"id":"CVE-2026-121367","kind":"vulnerability","aliases":["CVE-2026-121367"],"related":[],"title":"Arista EOS: RIPv2 silently enabled on management interfaces accepts unauthenticated routes","description":"On affected Arista EOS platforms with Routing Information Protocol version 2 (RIPv2) configured, under certain conditions, RIPv2 might be silently enabled on management interfaces even when the RIP agent intends to disable it. It allows an unauthenticated attacker with access to the adjacent network to send crafted RIPv2 route advertisements to the device's management IP address. The device could accept and install those routes without authentication.\n\nSuccessful exploitation could allow the attacker to redirect traffic flows to an attacker-controlled destination, install more-specific routes that blackhole legitimate traffic, or otherwise disrupt network reachability for systems whose traffic passes through the affected device.","summary":"On some Arista EOS platforms with RIPv2 configured, RIPv2 can be enabled on management interfaces even when disabled in config. An attacker on the adjacent network can send crafted RIPv2 advertisements that the device installs without authentication, redirecting or blackholing traffic.","severity":"critical","cvss":9.6,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["arista-eos","infrastructure","network","ripv2"],"not_affected_if":["ripv2-not-configured"],"how_to_check":"- Check whether RIP is configured: 'show running-config section router rip' on the EOS device; if there is no router rip configuration, the NVD text gives no exposure path.\n- Affected and fixed EOS releases: unknown until Arista's advisory for CVE-2026-121367 is found. Compare your 'show version' output against it.","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":"2026-11-10T20:47:17+00:00","updated_at":"2026-11-10T20:49:55+00:00","category":"infrastructure","confidence":0.4,"triage":{"at":"2026-11-10T20:47:17Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"Arista EOS: RIPv2 silently enabled on management interfaces accepts unauthenticated routes","impact":"high","summary":"On some Arista EOS platforms with RIPv2 configured, RIPv2 can be enabled on management interfaces even when disabled in config. An attacker on the adjacent network can send crafted RIPv2 advertisements that the device installs without authentication, redirecting or blackholing traffic.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["arista-eos","network","ripv2"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"Attacker redirects or blackholes network traffic through the affected device","analyst_note":"Find the Arista security advisory for CVE-2026-121367 to get affected and fixed EOS versions and the workaround for disabling RIPv2 on management interfaces.","how_to_check":"- Check whether RIPv2 is configured on the device and whether it is active on management interfaces (the sources do not name the exact command)\n- Review the affected EOS release list in the vendor advisory: unknown","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["ripv2-not-configured"],"who_is_affected":"Teams running Arista EOS network switches or routers with RIPv2 configured, where the management interface is reachable from an adjacent network. The sources do not list the affected EOS versions, so whether a given device is exposed is unknown. Devices not running RIPv2 are likely not affected, but the sources do not confirm this.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"yes","severity_if_unknown":"critical"},"cost_usd":0.000761,"input_tokens":4680,"output_tokens":585,"severity_before":"critical"},"analyst_status":"done","analyst_note":"Find the Arista security advisory for CVE-2026-121367 to get affected and fixed EOS versions and the workaround for disabling RIPv2 on management interfaces.","search":"'-121367':14A,17A '-2026':13A,16A '2':75C 'accept':9A,125C 'access':104C 'address':121C 'adjac':48B,107C 'advertis':54B,114C 'affect':66C,169C 'agent':93C 'allow':99C,135C 'arista':1A,19B,26B,67C 'arista-eo':18B 'attack':45B,102C,137C,145C 'attacker-control':144C 'authent':60B,131C 'blackhol':63B,154C 'certain':79C 'condit':80C 'config':43B 'configur':31B,77C 'control':146C 'could':124C,134C 'craft':52B,111C 'cve':12A,15A 'destin':147C 'devic':57B,117C,123C,170C 'disabl':41B,96C 'disrupt':159C 'enabl':5A,35B,85C 'eo':2A,20B,27B,68C 'even':39B,89C 'exploit':133C 'flow':141C 'inform':72C 'infrastructur':21B 'instal':58B,127C,148C 'intend':94C 'interfac':8A,38B,88C 'ip':120C 'legitim':155C 'manag':7A,37B,87C,119C 'might':82C 'more-specif':149C 'network':22B,49B,108C,160C 'otherwis':158C 'pass':166C 'platform':28B,69C 'protocol':73C 'reachabl':161C 'redirect':61B,139C 'rip':92C 'ripv2':3A,23B,30B,32B,53B,76C,81C,112C 'rout':11A,71C,113C,129C,152C 'send':51B,110C 'silent':4A,84C 'specif':151C 'success':132C 'system':163C 'traffic':64B,140C,156C,165C 'unauthent':10A,101C 'version':74C 'whose':164C 'without':59B,130C","nicknames":[],"mitigations":[],"who_affected":"Teams running Arista EOS switches or routers with RIPv2 configured, where an attacker on the adjacent network can reach the management IP address. Affected EOS versions are not yet published in any source we could read, so exposure of a given device is unconfirmed. Devices without RIPv2 configured are the likely skip, as the description only covers platforms with RIPv2 configured.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"unknown","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["aristaeos","critical","infrastructure","network","ripv2"],"campaign_type":null,"search_a":"'-121367':14A,17A '-2026':13A,16A 'accept':9A 'arista':1A 'cve':12A,15A 'enabl':5A 'eo':2A 'interfac':8A 'manag':7A 'ripv2':3A 'rout':11A 'silent':4A 'unauthent':10A","search_b":"'adjac':48B 'advertis':54B 'arista':19B,26B 'arista-eo':18B 'attack':45B 'authent':60B 'blackhol':63B 'config':43B 'configur':31B 'craft':52B 'devic':57B 'disabl':41B 'enabl':35B 'eo':20B,27B 'even':39B 'infrastructur':21B 'instal':58B 'interfac':38B 'manag':37B 'network':22B,49B 'platform':28B 'redirect':61B 'ripv2':23B,30B,32B,53B 'send':51B 'traffic':64B 'without':59B","search_c":"'2':75C 'accept':125C 'access':104C 'address':121C 'adjac':107C 'advertis':114C 'affect':66C,169C 'agent':93C 'allow':99C,135C 'arista':67C 'attack':102C,137C,145C 'attacker-control':144C 'authent':131C 'blackhol':154C 'certain':79C 'condit':80C 'configur':77C 'control':146C 'could':124C,134C 'craft':111C 'destin':147C 'devic':117C,123C,170C 'disabl':96C 'disrupt':159C 'enabl':85C 'eo':68C 'even':89C 'exploit':133C 'flow':141C 'inform':72C 'instal':127C,148C 'intend':94C 'interfac':88C 'ip':120C 'legitim':155C 'manag':87C,119C 'might':82C 'more-specif':149C 'network':108C,160C 'otherwis':158C 'pass':166C 'platform':69C 'protocol':73C 'reachabl':161C 'redirect':139C 'rip':92C 'ripv2':76C,81C,112C 'rout':71C,113C,129C,152C 'send':110C 'silent':84C 'specif':151C 'success':132C 'system':163C 'traffic':140C,156C,165C 'unauthent':101C 'version':74C 'whose':164C 'without':130C","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:A/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/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-2026-121367","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121367","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},{"source":"analyst","external_id":"CVE-2026-121367:2711","url":null,"severity":null,"published_at":"2026-11-10T20:49:55+00:00","modified_at":"2026-11-10T20:49:55+00:00","first_seen_at":"2026-11-10T20:49:55+00:00","fetched_at":"2026-11-10T20:49:55+00:00","note":"Arista advisory for this CVE not found (published today; arista.com advisories page is behind a client challenge, searches show only other 2026 advisories). Only NVD text available; no affected/fixed EOS versions, no workaround. Revisit when the Arista Security Advisory is indexed (check arista.com/en/support/advisories-notices)."}],"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"}