{"id":"CVE-2026-75491","kind":"vulnerability","aliases":["CVE-2026-75491"],"related":[],"title":"Cudy TR3000 router: MQTT login bypass lets attackers run commands as root","description":"Cudy TR3000 before 2.5.42 contains an authentication bypass vulnerability in the Mosquitto plugin auth_plugin_jwt.so that accepts unsigned JWTs using alg none. Attackers holding any Cudy-trusted client certificate can authenticate as admincudydevice on port 8883 and publish batchcmd requests to execute commands as root.","summary":"Cudy TR3000 routers before 2.5.42 have a Mosquitto plugin that accepts unsigned JSON Web Tokens using the alg none setting. An attacker holding any Cudy-trusted client certificate can log in as the admin device on port 8883 and publish batch command requests that run as root.","severity":"critical","cvss":9.2,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["cudy","infrastructure","iot","mosquitto","mqtt","routers","tr3000"],"not_affected_if":["firmware-2.5.42-or-later"],"how_to_check":"- Check the router firmware version in the admin interface; versions below `2.5.42` are in the affected range.\n- Check whether the Mosquitto broker on port `8883` is reachable from the network.","fix":"- Cudy TR3000: move to `2.5.42` or later.","status":"open","published_at":"2026-11-13T10:18:16+00:00","first_seen_at":"2026-11-13T10:47:35+00:00","triaged_at":"2026-11-13T10:48:28+00:00","updated_at":"2026-11-13T10:48:28+00:00","category":"infrastructure","confidence":0.7,"triage":{"at":"2026-11-13T10:48:28Z","model":"claude-haiku-5-5","output":{"fix":"- Cudy TR3000: move to `2.5.42` or later.","reach":"network","title":"Cudy TR3000 router: MQTT login bypass lets attackers run commands as root","impact":"high","summary":"Cudy TR3000 routers before 2.5.42 have a Mosquitto plugin that accepts unsigned JSON Web Tokens using the alg none setting. An attacker holding any Cudy-trusted client certificate can log in as the admin device on port 8883 and publish batch command requests that run as root.","audience":"everyone","category":"infrastructure","nicknames":[],"who_cares":["cudy","tr3000","mqtt","mosquitto","routers","iot"],"confidence":0.7,"fix_status":"available","needs_auth":"yes","worst_case":"Attacker runs commands as root on the router","analyst_note":"Confirm whether the MQTT broker on port 8883 is enabled by default and how the trusted client certificates are issued; see the VulnCheck advisory linked in the sources.","how_to_check":"- Check the router firmware version in the admin interface; versions below `2.5.42` are in the affected range.\n- Check whether the Mosquitto broker on port `8883` is reachable from the network.\n- unknown for any other check: the sources do not say how to inspect the plugin file `auth_plugin_jwt.so`.","plain_action":"Update your Cudy TR3000 router to firmware 2.5.42 or later.","product_name":"","needs_analyst":true,"not_affected_if":["firmware-2.5.42-or-later"],"who_is_affected":"Owners of Cudy TR3000 routers running firmware before 2.5.42 are exposed, and the flaw is reachable through the MQTT broker on port 8883. An attacker needs a client certificate that Cudy trusts, so devices without such access are less exposed, but the exact certificate distribution is unknown from the sources.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000804,"input_tokens":4618,"output_tokens":684,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-2026':14A,17A '-75491':15A,18A '2.5.42':30B,77C '8883':64B,109C 'accept':36B,89C 'admin':60B 'admincudydevic':106C 'alg':43B,93C 'attack':8A,47B,95C 'auth_plugin_jwt.so':87C 'authent':80C,104C 'batch':67B 'batchcmd':112C 'bypass':6A,81C 'certif':54B,102C 'client':53B,101C 'command':10A,68B,116C 'contain':78C 'cudi':1A,19B,26B,51B,74C,99C 'cudy-trust':50B,98C 'cve':13A,16A 'devic':61B 'execut':115C 'hold':48B,96C 'infrastructur':20B 'iot':21B 'json':38B 'jwts':91C 'let':7A 'log':56B 'login':5A 'mosquitto':22B,33B,85C 'mqtt':4A,23B 'none':44B,94C 'plugin':34B,86C 'port':63B,108C 'publish':66B,111C 'request':69B,113C 'root':12A,73B,118C 'router':3A,24B,28B 'run':9A,71B 'set':45B 'token':40B 'tr3000':2A,25B,27B,75C 'trust':52B,100C 'unsign':37B,90C 'use':41B,92C 'vulner':82C 'web':39B","nicknames":[],"mitigations":[],"who_affected":"Owners of Cudy TR3000 routers running firmware before 2.5.42 are exposed, and the flaw is reachable through the MQTT broker on port 8883. An attacker needs a client certificate that Cudy trusts, so devices without such access are less exposed, but the exact certificate distribution is unknown from the sources.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"everyone","plain_action":"Update your Cudy TR3000 router to firmware 2.5.42 or later.","pkeys":[],"ptokens":[],"labels":["critical","cudy","infrastructure","iot","mosquitto","mqtt","routers","tr3000"],"campaign_type":null,"search_a":"'-2026':14A,17A '-75491':15A,18A 'attack':8A 'bypass':6A 'command':10A 'cudi':1A 'cve':13A,16A 'let':7A 'login':5A 'mqtt':4A 'root':12A 'router':3A 'run':9A 'tr3000':2A","search_b":"'2.5.42':30B '8883':64B 'accept':36B 'admin':60B 'alg':43B 'attack':47B 'batch':67B 'certif':54B 'client':53B 'command':68B 'cudi':19B,26B,51B 'cudy-trust':50B 'devic':61B 'hold':48B 'infrastructur':20B 'iot':21B 'json':38B 'log':56B 'mosquitto':22B,33B 'mqtt':23B 'none':44B 'plugin':34B 'port':63B 'publish':66B 'request':69B 'root':73B 'router':24B,28B 'run':71B 'set':45B 'token':40B 'tr3000':25B,27B 'trust':52B 'unsign':37B 'use':41B 'web':39B","search_c":"'2.5.42':77C '8883':109C 'accept':89C 'admincudydevic':106C 'alg':93C 'attack':95C 'auth_plugin_jwt.so':87C 'authent':80C,104C 'batchcmd':112C 'bypass':81C 'certif':102C 'client':101C 'command':116C 'contain':78C 'cudi':74C,99C 'cudy-trust':98C 'execut':115C 'hold':96C 'jwts':91C 'mosquitto':85C 'none':94C 'plugin':86C 'port':108C 'publish':111C 'request':113C 'root':118C 'tr3000':75C 'trust':100C 'unsign':90C 'use':92C 'vulner':82C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-13T10:18:16+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/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:X/R:X/V:X/RE:X/U:X","cvss_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-75491","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-75491","severity":null,"published_at":"2026-11-13T10:18:16+00:00","modified_at":"2026-11-13T10:18:16+00:00","first_seen_at":"2026-11-13T10:47:35+00:00","fetched_at":"2026-11-13T10:47:35+00:00","note":null}],"documents":[{"id":145503,"url":"https://www.vulncheck.com/advisories/cudy-tr3000-before-2.5.42-mqtt-jwt-authentication-bypass-via-alg-none-tokens","title":"Third-party advisory: www.vulncheck.com","kind":"advisory","source":"nvd","publisher":"research","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":"Third-party advisory: www.vulncheck.com"}],"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"}