dns,net: reject hostnames with embedded NUL bytes

dns,net: reject hostnames with embedded NUL bytes

Ref: https://hackerone.com/reports/3656716
PR-URL: https://github.com/nodejs-private/node-private/pull/868
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
CVE-ID: CVE-2026-48930
Refs: https://hackerone.com/reports/3656716
origin: backport, https://github.com/nodejs/node/commit/c551a51d0c58dfc91961fb3f24c2c86af6183eca
Bug: https://nodejs.org/en/blog/vulnerability/june-2026-security-releases#embedded-nul-hostnames-can-lead-to-silent-authority-rebinding-due-to-c-string-trunc

Gbp-Pq: Topic sec
Gbp-Pq: Name CVE-2026-48930.patch