diff --git a/SECURITY_AUDIT_1_TASKS.md b/SECURITY_AUDIT_1_TASKS.md
index 70b22485..8f38b73c 100644
--- a/SECURITY_AUDIT_1_TASKS.md
+++ b/SECURITY_AUDIT_1_TASKS.md
@@ -71,6 +71,8 @@ Done when:
 
 ### 3. Add an auth surface regression gate for Node Manager
 
+Status: Done. Added the missing HTML route build-contract check, websocket same-origin guard, template-page block, and CORS regression test; existing cookie and read-only dashboard tests were rerun on 2026-05-15.
+
 Why:
 
 The branch fixed important auth behavior: no anonymous WebUI mode, CORS removed, session cookies hardened, durable session token no longer copied into websocket auth, and read-only dashboard writes denied. A-grade security needs a regression gate so these do not slip back.
diff --git a/src/rust/lqosd/src/node_manager/js_build/test-build-contract.sh b/src/rust/lqosd/src/node_manager/js_build/test-build-contract.sh
index 0740be56..0e80bd29 100755
--- a/src/rust/lqosd/src/node_manager/js_build/test-build-contract.sh
+++ b/src/rust/lqosd/src/node_manager/js_build/test-build-contract.sh
@@ -51,6 +51,21 @@ for page in "${served_pages[@]}"; do
   [[ -f "${STATIC_DIR}/${page}" ]] || fail "Page is served by static_pages.rs but missing from static2: ${page}"
 done
 
+declare -A directly_handled_html=(
+  ["first-run.html"]=1
+  ["login.html"]=1
+  ["template.html"]=1
+)
+
+for html_path in "${STATIC_DIR}"/*.html; do
+  [[ -e "${html_path}" ]] || continue
+  page="$(basename "${html_path}")"
+  [[ -n "${directly_handled_html[${page}]:-}" ]] && continue
+  if ! printf '%s\n' "${served_pages[@]}" | grep -qx -- "${page}"; then
+    fail "HTML page is present in static2 but not in the authenticated static_pages.rs route list: ${page}"
+  fi
+done
+
 required_template_assets=(
   "node_manager.css"
   "vendor/bootstrap.min.css"
diff --git a/src/rust/lqosd/src/node_manager/run.rs b/src/rust/lqosd/src/node_manager/run.rs
index af46e0db..9f90aab1 100644
--- a/src/rust/lqosd/src/node_manager/run.rs
+++ b/src/rust/lqosd/src/node_manager/run.rs
@@ -10,7 +10,7 @@ use crate::system_stats::SystemStats;
 use anyhow::{Result, bail};
 use axum::Router;
 use axum::http::StatusCode;
-use axum::response::Redirect;
+use axum::response::{IntoResponse, Redirect, Response};
 use axum::routing::{get, post};
 use lqos_bus::BusRequest;
 use lqos_config::load_config;
@@ -58,6 +58,7 @@ pub async fn spawn_webserver(
         .route("/doLogin", post(auth::try_login))
         .route("/firstLogin", post(auth::first_user))
         .route("/health", get(health_check))
+        .route("/template.html", get(not_found))
         .route("/configuration.html", get(redirect_configuration_page))
         // Backwards compatible aliases for historical misspellings.
         .route_service(
@@ -106,3 +107,23 @@ async fn redirect_configuration_page() -> Redirect {
 async fn health_check() -> (StatusCode, &'static str) {
     (StatusCode::OK, "OK")
 }
+
+async fn not_found() -> Response {
+    StatusCode::NOT_FOUND.into_response()
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn node_manager_router_sources_do_not_enable_cors_layer() {
+        let sources = [
+            include_str!("run.rs"),
+            include_str!("local_api.rs"),
+            include_str!("ws.rs"),
+        ];
+        for source in sources {
+            assert!(!source.contains(concat!("Cors", "Layer")));
+            assert!(!source.contains(concat!("tower_http::", "cors")));
+        }
+    }
+}
diff --git a/src/rust/lqosd/src/node_manager/ws.rs b/src/rust/lqosd/src/node_manager/ws.rs
index 7e114924..da6c7ab1 100644
--- a/src/rust/lqosd/src/node_manager/ws.rs
+++ b/src/rust/lqosd/src/node_manager/ws.rs
@@ -38,8 +38,8 @@ use axum::{
         WebSocketUpgrade,
         ws::{Message, WebSocket},
     },
-    http::{HeaderMap, StatusCode, header},
-    response::IntoResponse,
+    http::{HeaderMap, StatusCode, Uri, header},
+    response::{IntoResponse, Response},
     routing::get,
 };
 use futures_util::{SinkExt, StreamExt};
@@ -203,7 +203,12 @@ async fn ws_handler(
     Extension(probe_client): Extension<ProbeClient>,
     Extension(shaper_query): Extension<Sender<ShaperQueryCommand>>,
     headers: HeaderMap,
-) -> impl IntoResponse {
+) -> Response {
+    if !websocket_origin_allowed(&headers) {
+        warn!("Rejected websocket upgrade with cross-origin Origin header");
+        return StatusCode::FORBIDDEN.into_response();
+    }
+
     let has_cookie = headers.contains_key(header::COOKIE);
     let user_agent = headers
         .get(header::USER_AGENT)
@@ -236,6 +241,39 @@ async fn ws_handler(
         )
         .await;
     })
+    .into_response()
+}
+
+fn websocket_origin_allowed(headers: &HeaderMap) -> bool {
+    let Some(origin) = headers
+        .get(header::ORIGIN)
+        .and_then(|value| value.to_str().ok())
+        .map(str::trim)
+    else {
+        return true;
+    };
+
+    let Some(host) = headers
+        .get(header::HOST)
+        .and_then(|value| value.to_str().ok())
+        .map(str::trim)
+    else {
+        return false;
+    };
+
+    let Ok(uri) = origin.parse::<Uri>() else {
+        return false;
+    };
+    let Some(scheme) = uri.scheme_str() else {
+        return false;
+    };
+    if scheme != "http" && scheme != "https" {
+        return false;
+    }
+
+    uri.authority()
+        .map(|authority| authority.as_str().eq_ignore_ascii_case(host))
+        .unwrap_or(false)
 }
 
 async fn handle_socket(socket: WebSocket, context: WsUpgradeContext) {
@@ -2713,12 +2751,13 @@ mod tests {
     use super::{
         can_write_dashboard_themes, decode_ws_request, maybe_schedule_lts_signup_shutdown,
         run_topology_manager_blocking_with_timeout, run_topology_manager_mutation_blocking,
+        websocket_origin_allowed,
     };
     use crate::node_manager::auth::LoginResult;
     use crate::node_manager::local_api::urgent::{UrgentList, UrgentStatus};
     use crate::node_manager::ws::messages::WsRequest;
     use crate::node_manager::ws::messages::{WsResponse, encode_ws_message};
-    use axum::http::StatusCode;
+    use axum::http::{HeaderMap, HeaderValue, StatusCode, header};
     use serde_cbor::Value as CborValue;
     use std::collections::BTreeMap;
     use std::sync::{
@@ -2977,6 +3016,15 @@ mod tests {
         entries.contains_key(&text("request_id"))
     }
 
+    fn origin_headers(host: &str, origin: Option<&str>) -> HeaderMap {
+        let mut headers = HeaderMap::new();
+        headers.insert(header::HOST, HeaderValue::from_str(host).unwrap());
+        if let Some(origin) = origin {
+            headers.insert(header::ORIGIN, HeaderValue::from_str(origin).unwrap());
+        }
+        headers
+    }
+
     #[test]
     fn read_only_websocket_users_cannot_write_dashboard_themes() {
         assert!(can_write_dashboard_themes(LoginResult::Admin));
@@ -2984,6 +3032,37 @@ mod tests {
         assert!(!can_write_dashboard_themes(LoginResult::Denied));
     }
 
+    #[test]
+    fn websocket_origin_allows_same_origin_and_non_browser_clients() {
+        assert!(websocket_origin_allowed(&origin_headers(
+            "node.example.test:9123",
+            Some("https://node.example.test:9123")
+        )));
+        assert!(websocket_origin_allowed(&origin_headers(
+            "node.example.test:9123",
+            None
+        )));
+    }
+
+    #[test]
+    fn websocket_origin_rejects_cross_origin_and_invalid_origin() {
+        assert!(!websocket_origin_allowed(&origin_headers(
+            "node.example.test:9123",
+            Some("https://evil.example.test")
+        )));
+        assert!(!websocket_origin_allowed(&origin_headers(
+            "node.example.test:9123",
+            Some("null")
+        )));
+
+        let mut headers = HeaderMap::new();
+        headers.insert(
+            header::ORIGIN,
+            HeaderValue::from_static("https://node.example.test:9123"),
+        );
+        assert!(!websocket_origin_allowed(&headers));
+    }
+
     #[test]
     fn decodes_urgent_status_with_request_id() {
         let payload = serde_cbor::to_vec(&map(vec![(