Is CVE-2026-123872 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-123872 being exploited in the wild.

How severe is CVE-2026-123872?

High severity, with a CVSS score of 8.1, published 11 November 2026.

Which products and versions are affected?

OpenJS Foundation Node.js 22.x, 24.x, 26.x.

Is there a fix for CVE-2026-123872?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-123872 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-123872?

Check whether you run OpenJS Foundation Node.js at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-123872: Node.js client certificate auth bypass via TLS 1.2 renegotiation servername change

CVE-2026-123872 · Severity: high · CVSS 8.1 · Published 2026-11-11

Node.js TLS servers that enforce different client-certificate policies per hostname can be bypassed when a client changes the servername during TLS 1.2 renegotiation while keeping its existing authentication. An attacker who authenticates for a permitted hostname can renegotiate the connection under a different servername to access protected endpoints it should not be authorized for, bypassing stricter authentication policies.

Technologies: OpenJS Foundation Node.js. Vendors: OpenJS Foundation.

Quick answers

Is CVE-2026-123872 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-123872 being exploited in the wild.
How severe is CVE-2026-123872?: High severity, with a CVSS score of 8.1, published 11 November 2026.
Which products and versions are affected?: OpenJS Foundation Node.js 22.x, 24.x, 26.x.
Is there a fix for CVE-2026-123872?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-123872 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-123872?: Check whether you run OpenJS Foundation Node.js at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

This vulnerability exploits TLS 1.2 renegotiation to allow clients to alter the servername (SNI) while preserving their client certificate authentication state. A server that applies per-hostname certificate policies (for example, admin-only mTLS on one host and ordinary client-cert auth on another) fails to re-validate the client certificate against the new hostname during renegotiation. The attacker must have valid client certificates for at least one permitted hostname but gains unauthorized access to stricter-policy endpoints.

Affected products

OpenJS Foundation Node.js 22.x, 24.x, 26.x

Timeline

2026-11-11: disclosed

References

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