{"id":"CVE-2026-120033","kind":"vulnerability","aliases":["CVE-2026-120033"],"related":[],"title":"FRRouting: bgpd keeps dead BGP sessions up when neighbor stops reading","description":"In FRRouting 10.1 and later, bgpd does not correctly close a BGP session when the Send Hold Timer (RFC 9687) expires, i.e. when a neighbor has stopped accepting data from the router for twice the hold time. The connection is closed, but bgpd still considers the session to be up.\n\n\nA BGP neighbor that keeps sending KEEPALIVEs but stops reading from its connection, at a time when the router has a large amount of data to send to it (for example while sending it a full routing table), can cause one of the following:\n\n  *  If the neighbor announced Graceful Restart support: bgpd crashes shortly after the session is closed (after the neighbor's announced restart time plus one keepalive interval), taking down all BGP sessions on the router. The neighbor can repeat this each time bgpd restarts.\n  *  Otherwise: the session stays stuck in the Established state. The neighbor's routes stay installed and keep being advertised to other peers, and the neighbor cannot reconnect until an operator runs \"clear bgp <neighbor>\".\n\nThe neighbor does not need to be malicious; an overloaded or stuck peer can trigger the same behavior.\n\n\nRequired configuration: no special configuration is needed. Any BGP neighbor with an established session can trigger the issue under default settings, for example:\n\n  router bgp 65001\n   neighbor 192.0.2.2 remote-as 65002\n\nGraceful Restart helper mode, which leads to the crash, is enabled by default. With default timers (keepalive 60s, hold time 180s), the session is closed about 6 minutes after the neighbor stops reading.","summary":"FRRouting 10.1 and later does not fully close a BGP session when the Send Hold Timer expires because a neighbor stopped reading data, so bgpd still treats the session as up. A neighbor that keeps sending KEEPALIVEs but stops reading can crash bgpd and take down all BGP sessions when Graceful Restart is announced, or leave the stale session and its routes stuck in Established.","severity":"medium","cvss":6.0,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["bgp","frrouting","network-operators","package","routers"],"not_affected_if":["frr-below-10.1"],"how_to_check":"- Run `vtysh -c 'show version'` to see whether the FRRouting version is 10.1 or later.\n- Run `vtysh -c 'show bgp summary'` to list neighbors and their state.\n- Check the router config for `bgp graceful-restart` or neighbors announcing Graceful Restart support.","fix":null,"status":"open","published_at":"2026-11-12T19:16:48+00:00","first_seen_at":"2026-11-12T19:40:13+00:00","triaged_at":"2026-11-12T19:40:56+00:00","updated_at":"2026-11-12T19:40:56+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-11-12T19:40:56Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"FRRouting: bgpd keeps dead BGP sessions up when neighbor stops reading","impact":"medium","summary":"FRRouting 10.1 and later does not fully close a BGP session when the Send Hold Timer expires because a neighbor stopped reading data, so bgpd still treats the session as up. A neighbor that keeps sending KEEPALIVEs but stops reading can crash bgpd and take down all BGP sessions when Graceful Restart is announced, or leave the stale session and its routes stuck in Established.","audience":"businesses","category":"package","nicknames":[],"who_cares":["frrouting","bgp","routers","network-operators"],"confidence":0.7,"fix_status":"unknown","needs_auth":"no","worst_case":"bgpd crashes, dropping all BGP sessions on the router","analyst_note":"Fixed version not stated in the sources; check the FRRouting security advisory and NVD entry CVE-2026-120033 for the patched 10.1.x release.","how_to_check":"- Run `vtysh -c 'show version'` to see whether the FRRouting version is 10.1 or later.\n- Run `vtysh -c 'show bgp summary'` to list neighbors and their state.\n- Check the router config for `bgp graceful-restart` or neighbors announcing Graceful Restart support.","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["frr-below-10.1"],"who_is_affected":"Any FRRouting 10.1 or later router running bgpd with an established BGP neighbor is exposed under default settings, since no special configuration is needed. Graceful Restart helper mode is enabled by default and turns the stuck-session case into a bgpd crash. Routers running older FRRouting releases are outside the stated range.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"no","severity_if_unknown":"medium"},"cost_usd":0.000827,"input_tokens":4991,"output_tokens":655,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-120033':14A,17A '-2026':13A,16A '10.1':26B,92C '180s':330C '192.0.2.2':305C '6':336C '60s':327C '65001':303C '65002':309C '9687':109C 'accept':117C 'advertis':245C 'amount':162C 'announc':78B,187C,203C 'behavior':277C 'bgp':5A,18B,34B,72B,101C,141C,213C,259C,286C,302C 'bgpd':2A,49B,67B,95C,132C,191C,225C 'cannot':252C 'caus':179C 'clear':258C 'close':32B,99C,130C,198C,334C 'configur':279C,282C 'connect':128C,152C 'consid':134C 'correct':98C 'crash':66B,192C,318C 'cve':12A,15A 'data':47B,118C,164C 'dead':4A 'default':297C,322C,324C 'enabl':320C 'establish':89B,234C,290C 'exampl':170C,300C 'expir':41B,110C 'follow':183C 'frrout':1A,19B,25B,91C 'full':175C 'fulli':31B 'grace':75B,188C,310C 'helper':312C 'hold':39B,106C,125C,328C 'i.e':111C 'instal':241C 'interv':209C 'issu':295C 'keep':3A,59B,144C,243C 'keepal':61B,146C,208C,326C 'larg':161C 'later':28B,94C 'lead':315C 'leav':80B 'malici':267C 'minut':337C 'mode':313C 'need':264C,284C 'neighbor':9A,44B,57B,114C,142C,186C,201C,219C,237C,251C,261C,287C,304C,340C 'network':21B 'network-oper':20B 'one':180C,207C 'oper':22B,256C 'otherwis':227C 'overload':269C 'packag':23B 'peer':248C,272C 'plus':206C 'read':11A,46B,64B,149C,342C 'reconnect':253C 'remot':307C 'remote-a':306C 'repeat':221C 'requir':278C 'restart':76B,189C,204C,226C,311C 'rfc':108C 'rout':86B,176C,239C 'router':24B,121C,158C,217C,301C 'run':257C 'send':38B,60B,105C,145C,166C,172C 'session':6A,35B,53B,73B,83B,102C,136C,196C,214C,229C,291C,332C 'set':298C 'short':193C 'special':281C 'stale':82B 'state':235C 'stay':230C,240C 'still':50B,133C 'stop':10A,45B,63B,116C,148C,341C 'stuck':87B,231C,271C 'support':190C 'tabl':177C 'take':69B,210C 'time':126C,155C,205C,224C,329C 'timer':40B,107C,325C 'treat':51B 'trigger':274C,293C 'twice':123C","nicknames":[],"mitigations":[],"who_affected":"Any FRRouting 10.1 or later router running bgpd with an established BGP neighbor is exposed under default settings, since no special configuration is needed. Graceful Restart helper mode is enabled by default and turns the stuck-session case into a bgpd crash. Routers running older FRRouting releases are outside the stated range.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["bgp","frrouting","medium","networkoperators","package","routers"],"campaign_type":null,"search_a":"'-120033':14A,17A '-2026':13A,16A 'bgp':5A 'bgpd':2A 'cve':12A,15A 'dead':4A 'frrout':1A 'keep':3A 'neighbor':9A 'read':11A 'session':6A 'stop':10A","search_b":"'10.1':26B 'announc':78B 'bgp':18B,34B,72B 'bgpd':49B,67B 'close':32B 'crash':66B 'data':47B 'establish':89B 'expir':41B 'frrout':19B,25B 'fulli':31B 'grace':75B 'hold':39B 'keep':59B 'keepal':61B 'later':28B 'leav':80B 'neighbor':44B,57B 'network':21B 'network-oper':20B 'oper':22B 'packag':23B 'read':46B,64B 'restart':76B 'rout':86B 'router':24B 'send':38B,60B 'session':35B,53B,73B,83B 'stale':82B 'still':50B 'stop':45B,63B 'stuck':87B 'take':69B 'timer':40B 'treat':51B","search_c":"'10.1':92C '180s':330C '192.0.2.2':305C '6':336C '60s':327C '65001':303C '65002':309C '9687':109C 'accept':117C 'advertis':245C 'amount':162C 'announc':187C,203C 'behavior':277C 'bgp':101C,141C,213C,259C,286C,302C 'bgpd':95C,132C,191C,225C 'cannot':252C 'caus':179C 'clear':258C 'close':99C,130C,198C,334C 'configur':279C,282C 'connect':128C,152C 'consid':134C 'correct':98C 'crash':192C,318C 'data':118C,164C 'default':297C,322C,324C 'enabl':320C 'establish':234C,290C 'exampl':170C,300C 'expir':110C 'follow':183C 'frrout':91C 'full':175C 'grace':188C,310C 'helper':312C 'hold':106C,125C,328C 'i.e':111C 'instal':241C 'interv':209C 'issu':295C 'keep':144C,243C 'keepal':146C,208C,326C 'larg':161C 'later':94C 'lead':315C 'malici':267C 'minut':337C 'mode':313C 'need':264C,284C 'neighbor':114C,142C,186C,201C,219C,237C,251C,261C,287C,304C,340C 'one':180C,207C 'oper':256C 'otherwis':227C 'overload':269C 'peer':248C,272C 'plus':206C 'read':149C,342C 'reconnect':253C 'remot':307C 'remote-a':306C 'repeat':221C 'requir':278C 'restart':189C,204C,226C,311C 'rfc':108C 'rout':176C,239C 'router':121C,158C,217C,301C 'run':257C 'send':105C,145C,166C,172C 'session':102C,136C,196C,214C,229C,291C,332C 'set':298C 'short':193C 'special':281C 'state':235C 'stay':230C,240C 'still':133C 'stop':116C,148C,341C 'stuck':231C,271C 'support':190C 'tabl':177C 'take':210C 'time':126C,155C,205C,224C,329C 'timer':107C,325C 'trigger':274C,293C 'twice':123C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-12T19:16:48+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/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:N/R:A/V:X/RE:X/U:X","cvss_by":"57a55968-44ac-464c-a794-6ba3baad09c4","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-120033","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120033","severity":null,"published_at":"2026-11-12T19:16:48+00:00","modified_at":"2026-11-12T19:16:48+00:00","first_seen_at":"2026-11-12T19:40:13+00:00","fetched_at":"2026-11-12T19:40:13+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"}