{"id":"CVE-2026-111711","kind":"vulnerability","aliases":["CVE-2026-111711"],"related":[],"title":"Netcore NR256CN through 1.5.140116 contains a pre-authentication stack overflow vulnerability in the Boa web…","description":"Netcore NR256CN through 1.5.140116 contains a pre-authentication stack overflow vulnerability in the Boa web server's user_ok() function, which copies Basic-auth usernames with unbounded strcpy() calls into 64-byte stack buffers. Unauthenticated attackers can send a username longer than 63 bytes to any protected /router/*.cgi route to crash the main Boa process or potentially execute code.","summary":"Netcore NR256CN routers through firmware 1.5.140116 have a stack overflow in the Boa web server's Basic-auth check, where an overlong username is copied into a 64-byte buffer without a length limit. An unauthenticated attacker can crash the web server or potentially run code on the device.","severity":"critical","cvss":9.8,"epss":null,"exploited":false,"exploited_at":null,"products":[{"name":"NR256CN","fixed":[],"affected":"<= 1.5.140116","ecosystem":"vendor"}],"ecosystems":[],"tags":["boa-web-server","embedded","infrastructure","netcore","nr256cn","routers"],"not_affected_if":["admin-interface-not-exposed"],"how_to_check":"Log in to the router admin page and read the firmware version (System/Status page); NR256CN on 1.5.140116 or earlier is affected. Check whether the web admin (Boa, /router/*.cgi) is reachable from WAN or from untrusted LAN segments, e.g. scan your public IP on the admin port (80/8080).","fix":"No fixed firmware published as of 2026-10-23 (unknown; check Netcore support for a build newer than 1.5.140116). Mitigation: disable WAN/remote administration, restrict admin interface to a trusted management host, replace the device if it must be internet-facing.","status":"open","published_at":"2026-10-16T18:17:55+00:00","first_seen_at":"2026-10-23T21:57:13+00:00","triaged_at":"2026-10-23T22:04:57+00:00","updated_at":"2026-10-23T23:28:44+00:00","category":"infrastructure","confidence":0.75,"triage":{"at":"2026-10-23T22:04:57Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"network","impact":"high","summary":"Netcore NR256CN routers through firmware 1.5.140116 have a stack overflow in the Boa web server's Basic-auth check, where an overlong username is copied into a 64-byte buffer without a length limit. An unauthenticated attacker can crash the web server or potentially run code on the device.","category":"infrastructure","who_cares":["netcore","nr256cn","routers","boa-web-server"],"confidence":0.6,"needs_auth":"no","worst_case":"Unauthenticated attacker may execute code on the router","analyst_note":"Check the vendor or NVD advisory for a fixed firmware version and whether the web admin interface is reachable from WAN; sources gave no fix or check steps.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["admin-interface-not-exposed"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000452,"input_tokens":2804,"output_tokens":343,"severity_before":"critical"},"analyst_status":"done","analyst_note":"Check the vendor or NVD advisory for a fixed firmware version and whether the web admin interface is reachable from WAN; sources gave no fix or check steps.","search":"'-111711':19A,22A '-2026':18A,21A '/router':132C '1.5.140116':4A,38B,86C '63':127C '64':61B,115C 'attack':70B,120C 'auth':51B,108C 'authent':9A,91C 'basic':50B,107C 'basic-auth':49B,106C 'boa':15A,25B,45B,97C,139C 'boa-web-serv':24B 'buffer':63B,118C 'byte':62B,116C,128C 'call':113C 'cgi':133C 'check':52B 'code':79B,144C 'contain':5A,87C 'copi':58B,105C 'crash':72B,136C 'cve':17A,20A 'devic':82B 'embed':28B 'execut':143C 'firmwar':37B 'function':103C 'infrastructur':29B 'length':66B 'limit':67B 'longer':125C 'main':138C 'netcor':1A,30B,33B,83C 'nr256cn':2A,23A,31B,34B,84C 'ok':102C 'overflow':11A,42B,93C 'overlong':55B 'potenti':77B,142C 'pre':8A,90C 'pre-authent':7A,89C 'process':140C 'protect':131C 'rout':134C 'router':32B,35B 'run':78B 'send':122C 'server':27B,47B,75B,99C 'stack':10A,41B,92C,117C 'strcpi':112C 'unauthent':69B,119C 'unbound':111C 'user':101C 'usernam':56B,109C,124C 'vulner':12A,94C 'web':16A,26B,46B,74B,98C 'without':64B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-16T18:17:55+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/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-2026-111711","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-111711","severity":null,"published_at":"2026-10-16T18:17:55+00:00","modified_at":"2026-10-16T22:17:23+00:00","first_seen_at":"2026-10-23T21:57:13+00:00","fetched_at":"2026-10-23T22:28:55+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-111711:450","url":null,"severity":null,"published_at":"2026-10-23T23:28:44+00:00","modified_at":"2026-10-23T23:28:44+00:00","first_seen_at":"2026-10-23T23:28:44+00:00","fetched_at":"2026-10-23T23:28:44+00:00","note":"Read researcher (Nebusec) reference and VulnCheck advisory: affected NR256CN firmware <= 1.5.140116, no vendor advisory or fixed version found anywhere; PoC withheld, no exploitation known, not in KEV. No X search done (obscure device, CVE-id-only coverage from aggregators)."}],"documents":[{"id":1984,"url":"https://github.com/lukadqq/netcore-router-public-refs/blob/a44d562736b41c944223297e9144d2ad7fa2aff1/2026.10.15-netcore-nr256cn-basic-auth-stack-overflow.md","title":"Nebusec: NR256CN Basic-auth stack overflow in user_ok (researcher reference)","kind":"advisory","source":"analyst","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null},{"id":1985,"url":"https://www.vulncheck.com/advisories/netcore-nr256cn-through-1.5.140116-pre-auth-stack-overflow-via-boa-user-ok","title":"VulnCheck advisory: Netcore NR256CN pre-auth stack overflow","kind":"advisory","source":"analyst","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}