diff --git a/client/tailscale/apitype/apitype.go b/client/tailscale/apitype/apitype.go
index d10e20533..14b82cbbf 100644
--- a/client/tailscale/apitype/apitype.go
+++ b/client/tailscale/apitype/apitype.go
@@ -7,6 +7,9 @@ package apitype
 
 import "tailscale.com/tailcfg"
 
+// LocalAPIHost is the Host header value used by the LocalAPI.
+const LocalAPIHost = "local-tailscaled.sock"
+
 // WhoIsResponse is the JSON type returned by tailscaled debug server's /whois?ip=$IP handler.
 type WhoIsResponse struct {
 	Node        *tailcfg.Node
diff --git a/client/tailscale/localclient.go b/client/tailscale/localclient.go
index 07319e277..8933675ec 100644
--- a/client/tailscale/localclient.go
+++ b/client/tailscale/localclient.go
@@ -197,7 +197,7 @@ func SetVersionMismatchHandler(f func(clientVer, serverVer string)) {
 }
 
 func (lc *LocalClient) send(ctx context.Context, method, path string, wantStatus int, body io.Reader) ([]byte, error) {
-	req, err := http.NewRequestWithContext(ctx, method, "http://local-tailscaled.sock"+path, body)
+	req, err := http.NewRequestWithContext(ctx, method, "http://"+apitype.LocalAPIHost+path, body)
 	if err != nil {
 		return nil, err
 	}
@@ -435,7 +435,7 @@ func (lc *LocalClient) DeleteWaitingFile(ctx context.Context, baseName string) e
 }
 
 func (lc *LocalClient) GetWaitingFile(ctx context.Context, baseName string) (rc io.ReadCloser, size int64, err error) {
-	req, err := http.NewRequestWithContext(ctx, "GET", "http://local-tailscaled.sock/localapi/v0/files/"+url.PathEscape(baseName), nil)
+	req, err := http.NewRequestWithContext(ctx, "GET", "http://"+apitype.LocalAPIHost+"/localapi/v0/files/"+url.PathEscape(baseName), nil)
 	if err != nil {
 		return nil, 0, err
 	}
@@ -472,7 +472,7 @@ func (lc *LocalClient) FileTargets(ctx context.Context) ([]apitype.FileTarget, e
 // A size of -1 means unknown.
 // The name parameter is the original filename, not escaped.
 func (lc *LocalClient) PushFile(ctx context.Context, target tailcfg.StableNodeID, size int64, name string, r io.Reader) error {
-	req, err := http.NewRequestWithContext(ctx, "PUT", "http://local-tailscaled.sock/localapi/v0/file-put/"+string(target)+"/"+url.PathEscape(name), r)
+	req, err := http.NewRequestWithContext(ctx, "PUT", "http://"+apitype.LocalAPIHost+"/localapi/v0/file-put/"+string(target)+"/"+url.PathEscape(name), r)
 	if err != nil {
 		return err
 	}
@@ -595,7 +595,7 @@ func (lc *LocalClient) DialTCP(ctx context.Context, host string, port uint16) (n
 		},
 	}
 	ctx = httptrace.WithClientTrace(ctx, &trace)
-	req, err := http.NewRequestWithContext(ctx, "POST", "http://local-tailscaled.sock/localapi/v0/dial", nil)
+	req, err := http.NewRequestWithContext(ctx, "POST", "http://"+apitype.LocalAPIHost+"/localapi/v0/dial", nil)
 	if err != nil {
 		return nil, err
 	}
diff --git a/ipn/localapi/localapi.go b/ipn/localapi/localapi.go
index 114eb1956..1535dc5e1 100644
--- a/ipn/localapi/localapi.go
+++ b/ipn/localapi/localapi.go
@@ -32,6 +32,7 @@ import (
 	"tailscale.com/ipn/ipnlocal"
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/net/netutil"
+	"tailscale.com/safesocket"
 	"tailscale.com/tailcfg"
 	"tailscale.com/tka"
 	"tailscale.com/types/logger"
@@ -129,6 +130,10 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "server has no local backend", http.StatusInternalServerError)
 		return
 	}
+	if r.Referer() != "" || r.Header.Get("Origin") != "" || !validHost(r.Host) {
+		http.Error(w, "invalid localapi request", http.StatusForbidden)
+		return
+	}
 	w.Header().Set("Tailscale-Version", version.Long)
 	if h.RequiredPassword != "" {
 		_, pass, ok := r.BasicAuth()
@@ -148,6 +153,24 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+// validHost reports whether h is a valid Host header value for a LocalAPI request.
+func validHost(h string) bool {
+	// The client code sends a hostname of "local-tailscaled.sock".
+	switch h {
+	case "", apitype.LocalAPIHost:
+		return true
+	}
+	// Otherwise, any Host header we see should at most be an ip:port.
+	ap, err := netip.ParseAddrPort(h)
+	if err != nil {
+		return false
+	}
+	if runtime.GOOS == "windows" && ap.Port() != safesocket.WindowsLocalPort {
+		return false
+	}
+	return ap.Addr().IsLoopback()
+}
+
 // handlerForPath returns the LocalAPI handler for the provided Request.URI.Path.
 // (the path doesn't include any query parameters)
 func handlerForPath(urlPath string) (h localAPIHandler, ok bool) {