GHSA-qrxm-fqhp-jwvm

Description

## Impact undici crashes the client process when a TLS 1.2 server renegotiates after the connection is established and presents a different, CA-trusted certificate whose hostname does not match the requested host. Node.js re-runs hostname verification on the renegotiated handshake and destroys the socket with `ERR_TLS_CERT_ALTNAME_INVALID`. undici's established socket error handler asserted that this error code could never occur, so the peer-controlled error became an uncaught `AssertionError` that terminates the Node.js process. Both the HTTP/1.1 and HTTP/2 paths are affected. A malicious or compromised HTTPS endpoint reached through undici or the global `fetch()` can crash the client with a single server-initiated renegotiation, taking down all in-flight requests and background work in the process. Only TLS 1.2 is affected, because TLS 1.3 does not support renegotiation. Exploitation does not require a CA compromise: the attacker controls the endpoint and can present two ordinary valid certificates, the first matching the requested URL and the second intentionally not matching it. ## Patches Upgrade to undici 6.29.1, 7.30.1, or 8.12.2. ## Workarounds Restrict outbound connections to TLS 1.3, for example by setting `connect: { minVersion: 'TLSv1.3', maxVersion: 'TLSv1.3' }` on the client or agent, so that renegotiation cannot occur, when the target endpoints support TLS 1.3.