Node.js is vulnerable to a client certificate authentication bypass via TLS 1.2 renegotiation servername change

A client certificate authentication bypass in Node.js TLS lets a client change the servername during TLS 1.2 renegotiation to reach endpoints it was not authorized for. On a server that applies different client-certificate policies per hostname, for example stricter admin-only client-cert auth on one host and ordinary client-cert auth on another, a client that authenticates for a permitted host can renegotiate the TLS 1.2 connection under a different servername and carry its existing authentication to the protected host, bypassing the stricter policy. This vulnerability affects Node.js 26.x, 24.x, and 22.x.

The affected component does not establish the requesting party's identity reliably before granting access.

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may bypass an access boundary or take over an account.