{"id":"CVE-2026-128886","kind":"vulnerability","aliases":["CVE-2026-128886"],"related":[],"title":"dbus: stalled nonce-tcp connections block new clients, causing denial of service","description":"A flaw was found in dbus when configured with the nonce-tcp transport. An unauthenticated attacker able to connect to an exposed listener can cause a Denial of Service (DoS) by opening a connection and withholding the expected authentication token. Because the server processes this verification without enforcing a timeout, the stalled connection blocks the accept process and prevents legitimate clients from establishing new connections.","summary":"When dbus runs with the nonce-tcp transport, a connection that never sends its authentication token is not timed out. Such a connection blocks the accept loop so legitimate clients cannot connect.","severity":"medium","cvss":6.2,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["dbus","infrastructure","linux","self-hosted"],"not_affected_if":["default-config","local-socket-only"],"how_to_check":"- Check whether the dbus daemon is configured with the `nonce-tcp` transport in its dbus configuration files.\n- Check the dbus version with `dbus-daemon --version`; the sources do not name affected or fixed versions.","fix":null,"status":"open","published_at":"2026-11-13T22:17:23+00:00","first_seen_at":"2026-11-13T22:33:34+00:00","triaged_at":"2026-11-13T22:34:34+00:00","updated_at":"2026-11-13T22:34:34+00:00","category":"infrastructure","confidence":0.5,"triage":{"at":"2026-11-13T22:34:34Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","title":"dbus: stalled nonce-tcp connections block new clients, causing denial of service","impact":"low","summary":"When dbus runs with the nonce-tcp transport, a connection that never sends its authentication token is not timed out. Such a connection blocks the accept loop so legitimate clients cannot connect.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["dbus","linux","self-hosted"],"confidence":0.5,"fix_status":"unknown","needs_auth":"no","worst_case":"Denial of service: legitimate clients cannot establish new dbus connections.","analyst_note":"Find the NVD entry's affected version ranges and whether a dbus upstream fix or advisory exists; the sources give none.","how_to_check":"- Check whether the dbus daemon is configured with the `nonce-tcp` transport in its dbus configuration files.\n- Check the dbus version with `dbus-daemon --version`; the sources do not name affected or fixed versions.","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["default-config","local-socket-only"],"who_is_affected":"Only systems where dbus is configured with the nonce-tcp transport and its listener is reachable by an attacker. Default local-socket setups are not described as affected. The sources do not give version ranges.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000708,"input_tokens":4569,"output_tokens":502,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-128886':16A,19A '-2026':15A,18A 'abl':76C 'accept':52B,115C 'attack':75C 'authent':41B,98C 'block':7A,50B,113C 'cannot':57B 'caus':10A,84C 'client':9A,56B,120C 'configur':66C 'connect':6A,36B,49B,58B,78C,93C,112C,124C 'cve':14A,17A 'dbus':1A,20B,27B,64C 'denial':11A,86C 'dos':89C 'enforc':107C 'establish':122C 'expect':97C 'expos':81C 'flaw':60C 'found':62C 'host':25B 'infrastructur':21B 'legitim':55B,119C 'linux':22B 'listen':82C 'loop':53B 'never':38B 'new':8A,123C 'nonc':4A,32B,70C 'nonce-tcp':3A,31B,69C 'open':91C 'prevent':118C 'process':103C,116C 'run':28B 'self':24B 'self-host':23B 'send':39B 'server':102C 'servic':13A,88C 'stall':2A,111C 'tcp':5A,33B,71C 'time':45B 'timeout':109C 'token':42B,99C 'transport':34B,72C 'unauthent':74C 'verif':105C 'withhold':95C 'without':106C","nicknames":[],"mitigations":[],"who_affected":"Only systems where dbus is configured with the nonce-tcp transport and its listener is reachable by an attacker. Default local-socket setups are not described as affected. The sources do not give version ranges.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["dbus","infrastructure","linux","medium","selfhosted"],"campaign_type":null,"search_a":"'-128886':16A,19A '-2026':15A,18A 'block':7A 'caus':10A 'client':9A 'connect':6A 'cve':14A,17A 'dbus':1A 'denial':11A 'new':8A 'nonc':4A 'nonce-tcp':3A 'servic':13A 'stall':2A 'tcp':5A","search_b":"'accept':52B 'authent':41B 'block':50B 'cannot':57B 'client':56B 'connect':36B,49B,58B 'dbus':20B,27B 'host':25B 'infrastructur':21B 'legitim':55B 'linux':22B 'loop':53B 'never':38B 'nonc':32B 'nonce-tcp':31B 'run':28B 'self':24B 'self-host':23B 'send':39B 'tcp':33B 'time':45B 'token':42B 'transport':34B","search_c":"'abl':76C 'accept':115C 'attack':75C 'authent':98C 'block':113C 'caus':84C 'client':120C 'configur':66C 'connect':78C,93C,112C,124C 'dbus':64C 'denial':86C 'dos':89C 'enforc':107C 'establish':122C 'expect':97C 'expos':81C 'flaw':60C 'found':62C 'legitim':119C 'listen':82C 'new':123C 'nonc':70C 'nonce-tcp':69C 'open':91C 'prevent':118C 'process':103C,116C 'server':102C 'servic':88C 'stall':111C 'tcp':71C 'timeout':109C 'token':99C 'transport':72C 'unauthent':74C 'verif':105C 'withhold':95C 'without':106C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-13T22:17:23+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvss_by":"secalert@redhat.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-128886","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-128886","severity":null,"published_at":"2026-11-13T22:17:23+00:00","modified_at":"2026-11-13T22:17:23+00:00","first_seen_at":"2026-11-13T22:33:34+00:00","fetched_at":"2026-11-13T22:33:34+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"}