{"id":"CVE-2026-106072","kind":"vulnerability","aliases":["CVE-2026-106072"],"related":[],"title":"Node.js: TLS check lets DNS-only certificates impersonate IP endpoints","description":"A flaw in Node.js TLS hostname verification allows a certificate with only a DNS SAN to authenticate an IP endpoint when the client connects using a non-canonical IPv4 spelling, such as `0177.0.0.1`, `0x7f.0.0.1`, `2130706433` or `127.1`.\n\n`tls.checkServerIdentity()` did not classify these hosts as IP addresses, but normalized them to their canonical form and matched the result against the certificate DNS names. A certificate containing `DNS:127.0.0.1` and no `IP Address:127.0.0.1` SAN was therefore accepted, while the same certificate is correctly rejected for `127.0.0.1`. Exploitation requires a certificate with a numeric DNS SAN issued by a CA trusted by the client, and a platform resolver that accepts these spellings, such as glibc.\n\nThis vulnerability affects Node.js **26.x**, **24.x**, and **22.x**.","summary":"Node.js's tls.checkServerIdentity() normalizes non-canonical IPv4 spellings such as 0177.0.0.1, 0x7f.0.0.1, 2130706433 and 127.1, then matches them against certificate DNS names. A certificate with only a numeric DNS SAN, issued by a trusted CA, is accepted for the IP endpoint, so an attacker can impersonate that server.","severity":"medium","cvss":6.7,"epss":0.00306,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["glibc","node.js","poc-public","runtime","tls"],"not_affected_if":["no-numeric-dns-san-certs","non-glibc-resolver"],"how_to_check":"- Run `node --version` and check whether it starts with `22.`, `24.` or `26.`\n- Find code that calls `tls.checkServerIdentity()` or relies on default hostname verification for connections to IP addresses\n- Check whether the platform resolver is glibc, since the sources say exploitation requires a resolver that accepts these spellings","fix":"- unknown: the sources affected versions 26.x, 24.x and 22.x but do not name a patched Node.js release","status":"open","published_at":"2026-10-23T17:17:20+00:00","first_seen_at":"2026-10-23T21:57:34+00:00","triaged_at":"2026-10-25T03:45:29+00:00","updated_at":"2026-10-25T12:38:50+00:00","category":"runtime","confidence":0.7,"triage":{"at":"2026-10-25T03:45:29Z","model":"claude-haiku-5-5","output":{"fix":"- unknown: the sources affected versions 26.x, 24.x and 22.x but do not name a patched Node.js release","reach":"network","title":"Node.js: TLS check lets DNS-only certificates impersonate IP endpoints","impact":"medium","summary":"Node.js's tls.checkServerIdentity() normalizes non-canonical IPv4 spellings such as 0177.0.0.1, 0x7f.0.0.1, 2130706433 and 127.1, then matches them against certificate DNS names. A certificate with only a numeric DNS SAN, issued by a trusted CA, is accepted for the IP endpoint, so an attacker can impersonate that server.","category":"runtime","nicknames":[],"who_cares":["node.js","tls","glibc"],"confidence":0.7,"needs_auth":"unknown","worst_case":"attacker impersonates an IP-addressed TLS server; client trusts it","analyst_note":"Find the patched Node.js release lines in the NVD entry (https://nvd.nist.gov/vuln/detail/CVE-2026-106072) or the Node.js security advisory, and confirm the fix version for 22.x, 24.x and 26.x.","how_to_check":"- Run `node --version` and check whether it starts with `22.`, `24.` or `26.`\n- Find code that calls `tls.checkServerIdentity()` or relies on default hostname verification for connections to IP addresses\n- Check whether the platform resolver is glibc, since the sources say exploitation requires a resolver that accepts these spellings","needs_analyst":true,"not_affected_if":["no-numeric-dns-san-certs","non-glibc-resolver"],"who_is_affected":"Applications running Node.js 22.x, 24.x or 26.x that connect to IP-addressed TLS endpoints and verify certificates with the default hostname check. Exploitation needs a certificate with a numeric DNS SAN issued by a CA the client trusts, and a platform resolver such as glibc that accepts these IPv4 spellings. Teams that only connect by DNS name, or use only non-glibc resolvers, are less exposed.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.001384,"input_tokens":3608,"output_tokens":2047,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-106072':14A,17A '-2026':13A,16A '0177.0.0.1':36B,107C '0x7f.0.0.1':37B,108C '127.0.0.1':141C,146C,159C '127.1':40B,111C '2130706433':38B,109C '22':197C '24':194C '26':192C 'accept':62B,150C,182C 'address':120C,145C 'affect':190C 'allow':81C 'attack':69B 'authent':90C 'ca':60B,172C 'canon':31B,102C,126C 'certif':8A,45B,49B,83C,134C,138C,154C,163C 'check':3A 'classifi':115C 'client':96C,176C 'connect':97C 'contain':139C 'correct':156C 'cve':12A,15A 'dns':6A,46B,54B,87C,135C,140C,167C 'dns-on':5A 'endpoint':11A,66B,93C 'exploit':160C 'flaw':75C 'form':127C 'glibc':18B,187C 'host':117C 'hostnam':79C 'imperson':9A,71B 'ip':10A,65B,92C,119C,144C 'ipv4':32B,103C 'issu':56B,169C 'let':4A 'match':42B,129C 'name':47B,136C 'node.js':1A,19B,25B,77C,191C 'non':30B,101C 'non-canon':29B,100C 'normal':28B,122C 'numer':53B,166C 'platform':179C 'poc':21B 'poc-publ':20B 'public':22B 'reject':157C 'requir':161C 'resolv':180C 'result':131C 'runtim':23B 'san':55B,88C,147C,168C 'server':73B 'spell':33B,104C,184C 'therefor':149C 'tls':2A,24B,78C 'tls.checkserveridentity':27B,112C 'trust':59B,173C 'use':98C 'verif':80C 'vulner':189C 'x':193C,195C,198C","nicknames":[],"mitigations":[],"who_affected":"Applications running Node.js 22.x, 24.x or 26.x that connect to IP-addressed TLS endpoints and verify certificates with the default hostname check. Exploitation needs a certificate with a numeric DNS SAN issued by a CA the client trusts, and a platform resolver such as glibc that accepts these IPv4 spellings. Teams that only connect by DNS name, or use only non-glibc resolvers, are less exposed.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-23T17:17:20+00:00","kev":null,"cvss_vector":"CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L","cvss_by":"support@hackerone.com","poc_count":1,"sources":[{"source":"nvd","external_id":"CVE-2026-106072","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-106072","severity":null,"published_at":"2026-10-23T17:17:20+00:00","modified_at":"2026-10-23T19:42:24+00:00","first_seen_at":"2026-10-23T21:57:34+00:00","fetched_at":"2026-10-23T22:29:03+00:00","note":null},{"source":"github-poc","external_id":"CompleteTech-LLC/node-cve-2026-106072-check","url":"https://github.com/CompleteTech-LLC/node-cve-2026-106072-check","severity":null,"published_at":"2026-10-23T23:47:51+00:00","modified_at":null,"first_seen_at":"2026-10-23T23:55:02+00:00","fetched_at":"2026-10-23T23:55:02+00:00","note":null},{"source":"epss","external_id":"CVE-2026-106072","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-106072","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-25T12:38:50+00:00","fetched_at":"2026-10-25T12:38:50+00:00","note":null}],"documents":[{"id":2243,"url":"https://github.com/CompleteTech-LLC/node-cve-2026-106072-check","title":"CompleteTech-LLC/node-cve-2026-106072-check","kind":"poc","source":"github","text":"Standalone defensive checker project for CVE-2026-106072: Node.js: TLS noncanonical-IP DNS SAN acceptance. One exploit per repository; implementation pending.\n\nstars 0","published_at":"2026-10-23T23:47:51+00:00","relation":"poc","confidence":null,"note":"0 stars"}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}