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CVE-2026-123867

MEDIUMCVSS 4.2/10EPSS 0.15%

Last modified

CVE-2026-123867 is a medium-severity vulnerability rated 4.2/10 on the CVSS scale. 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. EPSS estimates a 0.15% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
4.2/10

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS Probability
0.15%

4.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
nodejsnode>= 0.0.0, < 22.23.5; >= 23.0.0, < 24.22.3; >= 25.0.0, < 26.13.1

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-123867?
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.
How severe is CVE-2026-123867?
CVE-2026-123867 has a CVSS score of 4.2/10 (MEDIUM severity). The EPSS model estimates a 0.15% probability of exploitation in the next 30 days.
How do I fix CVE-2026-123867?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST