---
id: "CVE-2026-106072"
kind: "vulnerability"
aliases: ["CVE-2026-106072"]
title: "Node.js: TLS check lets DNS-only certificates impersonate IP endpoints"
severity: "medium"
cvss: 6.7
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["glibc", "node.js", "poc-public", "runtime", "tls"]
not_affected_if: ["no-numeric-dns-san-certs", "non-glibc-resolver"]
published_at: "2026-10-23T17:17:20+00:00"
first_seen_at: "2026-10-23T21:57:34+00:00"
updated_at: "2026-10-25T03:45:29+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-106072", "first_seen_at": "2026-10-23T21:57:34+00:00"}, {"source": "github-poc", "url": "https://github.com/CompleteTech-LLC/node-cve-2026-106072-check", "first_seen_at": "2026-10-23T23:55:02+00:00"}]
---

# Node.js: TLS check lets DNS-only certificates impersonate IP endpoints

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.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `node --version` and check whether it starts with `22.`, `24.` or `26.`
- Find code that calls `tls.checkServerIdentity()` or relies on default hostname verification for connections to IP addresses
- 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

## Timeline

- 2026-10-23T21:57:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-106072
- 2026-10-23T23:55:02+00:00 github-poc https://github.com/CompleteTech-LLC/node-cve-2026-106072-check

## Documents

- [poc] CompleteTech-LLC/node-cve-2026-106072-check https://github.com/CompleteTech-LLC/node-cve-2026-106072-check

## From the sources

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`.

`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.

This vulnerability affects Node.js **26.x**, **24.x**, and **22.x**.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_