CVE-2026-84716: Automation-controller: automation-controller: instance install_bundle issues 10-year, non-revocable receptor mesh-ca certificates for caller-chosen (and case-variant impersonating) hostnames

A flaw was found in the automation-controller instance install-bundle endpoint. When a System Administrator downloads an execution/hop node's install bundle, the controller signs an X.509 certificate with the receptor mesh certificate authority in which the Common Name, DNS subject-alternative-name, and receptor node-id are taken verbatim from the caller-chosen instance hostname, with a hard-coded ten-year validity, a random serial, and no issuance log or revocation list. Because the hostname charset validator is case-insensitive while the uniqueness validator is case-sensitive, an administrator can register a case variant of an existing control node's hostname and obtain a mesh-CA-signed certificate that TLS peers, which match hostnames case-insensitively, accept as that control node. In managed/hosted deployments — where the customer holds controller superuser but the platform operator runs the mesh — this yields a long-lived, non-revocable mesh peer credential and, with an on-path position, TLS impersonation or interception of control/hybrid mesh nodes. It does not grant direct remote code execution, because receptor work submission is gated by a separate signing key not included in the bundle.