{"id":"CVE-2026-119776","kind":"vulnerability","aliases":["CVE-2026-119776"],"related":[],"title":"FRRouting: OSPFv3 accepts packets from non-link-local IPv6 hosts","description":"In all prior released versions of FRRouting, the OSPFv3 (for IPv6) implementation does not check that OSPFv3 packets have a link-local source address and either a link-local destination or one of the protocol multicast destination groups.  This may enable malicious actors to establish OSPFv3 adjacencies from unexpectedly, distant IPv6 hosts. Proper usage of OSPFv3 authentication trailers (RFC 7166, as is best practice) prevents full exploitation of this issue, though may allow a malicious actor to waste CPU on authentication checks.\n\n\n\nNote the linked PR #23935 is not sufficient to fix the issue as it only verifies the source address. It is the destination address that must be checked.","summary":"FRRouting's OSPFv3 implementation for IPv6 does not check that packets come from a link-local source and go to a link-local or protocol multicast destination. An attacker on a distant IPv6 host can establish OSPFv3 adjacencies with the router, and authentication trailers (RFC 7166) limit full exploitation but can still be used to waste CPU.","severity":"medium","cvss":6.1,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["frrouting","ipv6","ospfv3","routers","runtime"],"not_affected_if":["no-ospfv3","ospf-authentication-trailers"],"how_to_check":"- Check the FRRouting version with `vtysh -c 'show version'`; all prior released versions are listed as affected in the description.\n- Check whether OSPFv3 is enabled with `vtysh -c 'show ipv6 ospf6 interface'`.\n- Check whether OSPFv3 authentication trailers are configured on the interfaces.","fix":null,"status":"open","published_at":"2026-11-04T15:17:41+00:00","first_seen_at":"2026-11-04T15:27:29+00:00","triaged_at":"2026-11-04T15:28:28+00:00","updated_at":"2026-11-04T15:28:28+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-11-04T15:28:28Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"FRRouting: OSPFv3 accepts packets from non-link-local IPv6 hosts","impact":"low","summary":"FRRouting's OSPFv3 implementation for IPv6 does not check that packets come from a link-local source and go to a link-local or protocol multicast destination. An attacker on a distant IPv6 host can establish OSPFv3 adjacencies with the router, and authentication trailers (RFC 7166) limit full exploitation but can still be used to waste CPU.","audience":"businesses","category":"runtime","nicknames":[],"who_cares":["frrouting","ospfv3","routers","ipv6"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"Attacker forms unauthorized OSPFv3 adjacency and wastes router CPU","analyst_note":"Confirm the fixed FRRouting release and whether the destination-address check has landed; the sources only say PR #23935 is insufficient.","how_to_check":"- Check the FRRouting version with `vtysh -c 'show version'`; all prior released versions are listed as affected in the description.\n- Check whether OSPFv3 is enabled with `vtysh -c 'show ipv6 ospf6 interface'`.\n- Check whether OSPFv3 authentication trailers are configured on the interfaces.","plain_action":"","needs_analyst":true,"not_affected_if":["no-ospfv3","ospf-authentication-trailers"],"who_is_affected":"Routers and Linux hosts running FRRouting with OSPFv3 (IPv6) enabled are exposed. The description says authentication trailers per RFC 7166 prevent full exploitation, so teams using them face less risk. Teams not running OSPFv3 can skip it. The linked PR #23935 is stated as insufficient, so the source does not confirm a fixed release.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.00077,"input_tokens":4268,"output_tokens":687,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-119776':14A,17A '-2026':13A,16A '23935':170C '7166':70B,143C 'accept':3A 'actor':126C,159C 'address':106C,184C,189C 'adjac':62B,130C 'allow':156C 'attack':53B 'authent':67B,140C,164C 'best':146C 'check':31B,96C,165C,193C 'come':34B 'cpu':81B,162C 'cve':12A,15A 'destin':51B,113C,120C,188C 'distant':56B,133C 'either':108C 'enabl':124C 'establish':60B,128C 'exploit':73B,150C 'fix':175C 'frrout':1A,18B,23B,88C 'full':72B,149C 'go':42B 'group':121C 'host':11A,58B,135C 'implement':26B,93C 'ipv6':10A,19B,28B,57B,92C,134C 'issu':153C,177C 'limit':71B 'link':8A,38B,46B,103C,111C,168C 'link-loc':37B,45B,102C,110C 'local':9A,39B,47B,104C,112C 'malici':125C,158C 'may':123C,155C 'multicast':50B,119C 'must':191C 'non':7A 'non-link-loc':6A 'note':166C 'one':115C 'ospfv3':2A,20B,25B,61B,90C,98C,129C,139C 'packet':4A,33B,99C 'pr':169C 'practic':147C 'prevent':148C 'prior':84C 'proper':136C 'protocol':49B,118C 'releas':85C 'rfc':69B,142C 'router':21B,65B 'runtim':22B 'sourc':40B,105C,183C 'still':76B 'suffici':173C 'though':154C 'trailer':68B,141C 'unexpect':132C 'usag':137C 'use':78B 'verifi':181C 'version':86C 'wast':80B,161C","nicknames":[],"mitigations":[],"who_affected":"Routers and Linux hosts running FRRouting with OSPFv3 (IPv6) enabled are exposed. The description says authentication trailers per RFC 7166 prevent full exploitation, so teams using them face less risk. Teams not running OSPFv3 can skip it. The linked PR #23935 is stated as insufficient, so the source does not confirm a fixed release.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"unknown","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["frrouting","ipv6","medium","ospfv3","routers","runtime"],"campaign_type":null,"first_public_at":"2026-11-04T15:17:41+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/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:Y/R:X/V:X/RE:X/U:X","cvss_by":"57a55968-44ac-464c-a794-6ba3baad09c4","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-119776","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-119776","severity":null,"published_at":"2026-11-04T15:17:41+00:00","modified_at":"2026-11-04T15:17:41+00:00","first_seen_at":"2026-11-04T15:27:29+00:00","fetched_at":"2026-11-04T15:27:29+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}