CVE-2026-50192: Kerberos Hub private key (X-Kerberos-Hub-PrivateKey) leaked to cross-host redirect target due to redirect-following HTTP client without CheckRedirect

The Kerberos Hub upload path sends the agent’s Hub credentials in the custom X-Kerberos-Hub-PrivateKey and X-Kerberos-Hub-PublicKey request headers to the operator-configured Hub URL (config.HubURI). The HTTP client used (&http.Client{} in UploadKerberosHub) is constructed without a CheckRedirect policy, so it follows HTTP redirects automatically. Go’s net/http strips only sensitive headers (Authorization, Cookie, WWW-Authenticate) on a cross-host redirect; it does not strip custom headers such as X-Kerberos-Hub-PrivateKey. As a result, if the configured HubURI returns a cross-host 30x redirect, the Hub private key is forwarded verbatim to the redirect target, disclosing the credential to an unintended third party (CWE-200 / CWE-522).