# CVE-2026-123867: Node.js is vulnerable to a per-host mTLS authorization bypass via a CA-only SNI context failing open to the default CA

> A client with a certificate trusted by the default CA can bypass per-host mTLS authorization to reach protected hostnames in Node.js TLS servers.

- **Severity:** Medium 4.2 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Harmful if only installed:** No
- **Needs a specific call:** Yes (`CertCbDone`, `setSniContext`)
- **Fix available:** Yes
- **Published:** 11 Nov 2026
- **Updated:** 12 Nov 2026
- **Also known as:** ALPINE-CVE-2026-123867, BELL-CVE-2026-123867, DEBIAN-CVE-2026-123867, GHSA-xhqh-vr6v-3wgj, UBUNTU-CVE-2026-123867

## What is CVE-2026-123867?

CVE-2026-123867 is a medium-severity authentication bypass vulnerability in nodejs node, published on 11 Nov 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A per-host mutual-TLS authorization bypass in Node.js lets a client authorized for the default hostname reach a protected hostname it is not authorized for. When a TLS server assigns a hostname a different client-certificate CA with `server.addContext(host, { ca: protectedCA })` but no server certificate in that SNI context, the per-host client CA is never installed and the handshake falls back to the default client CA. In `src/crypto/crypto_tls.cc`, `CertCbDone` installs the SNI context's CA only when `setSniContext` succeeds, but `setSniContext` returns `false` for a context with no server certificate, so a CA-only SNI context silently keeps the default CA. A client holding a certificate trusted by the default CA, but not the protected CA, can therefore complete mTLS to the protected hostname and read its response even with `requestCert` and `rejectUnauthorized` enabled, while a client certified by the protected CA is rejected. This vulnerability affects Node.js 26.x, 24.x, and 22.x.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2026-123867?

An affected version is only exploitable if your software calls CertCbDone or setSniContext. Many projects that include it are not exposed.


## How do I fix CVE-2026-123867?

No fix published yet.

## Is CVE-2026-123867 being exploited?

There is no known exploitation of CVE-2026-123867 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123867 and fix it if it is affected.

What it is: CVE-2026-123867 is a medium-severity authentication bypass vulnerability in nodejs node, published on 11 Nov 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-123867 in the wild and no public exploit code.
Exposure: An affected version is only exploitable if your software calls CertCbDone or setSniContext. Many projects that include it are not exposed.

Affected product: nodejs node. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
   If an affected version is present, also search the code for calls to CertCbDone or setSniContext and report whether any exist.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-123867/ (Markdown: https://insights.sbomify.com/CVE-2026-123867/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123867
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123867
- OSV: https://osv.dev/vulnerability/CVE-2026-123867

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-123867/
Summaries are generated and may contain mistakes; the official description above is the record.