diff --git a/components/StreamEmbed.vue b/components/StreamEmbed.vue
index 538414a7..e1d9a8a5 100644
--- a/components/StreamEmbed.vue
+++ b/components/StreamEmbed.vue
@@ -224,7 +224,18 @@ export default {
       platform: Platform;
       embedId: string | null;
     } {
-      const url = new URL(link);
+      let url: URL;
+      try {
+        url = new URL(link);
+      } catch {
+        // Malformed link: nothing to embed.
+        return { platform: "iframe", embedId: null };
+      }
+      // Only http(s) may ever reach an iframe src. A javascript:/data: link
+      // would otherwise be embedded verbatim on a public match page.
+      if (url.protocol !== "http:" && url.protocol !== "https:") {
+        return { platform: "iframe", embedId: null };
+      }
       const hostname = url.hostname.toLowerCase();
 
       if (hostname.endsWith("twitch.tv")) {
@@ -392,6 +403,15 @@ export default {
       const playerRef = this.$refs.playerRef as HTMLDivElement | null;
       if (!playerRef || !url) return;
 
+      // Defense-in-depth alongside parseStreamLink: never embed a non-http(s)
+      // URL, even if a caller reaches this method with an unvetted value.
+      try {
+        const scheme = new URL(url).protocol;
+        if (scheme !== "http:" && scheme !== "https:") return;
+      } catch {
+        return;
+      }
+
       this.cleanupPlayer();
 
       const iframe = document.createElement("iframe");
@@ -400,6 +420,13 @@ export default {
       iframe.height = "100%";
       iframe.allow =
         "autoplay; fullscreen; encrypted-media; picture-in-picture";
+      // Constrain an arbitrary third-party embed: keep the player functional
+      // (scripts, its own origin, fullscreen/popups) but block it from
+      // navigating or driving the top-level 5stack window.
+      iframe.setAttribute(
+        "sandbox",
+        "allow-scripts allow-same-origin allow-popups allow-popups-to-escape-sandbox allow-presentation allow-forms",
+      );
       iframe.style.aspectRatio = "16 / 9";
       iframe.style.width = "100%";
       iframe.style.height = "100%";
diff --git a/components/match/MatchLiveStreams.vue b/components/match/MatchLiveStreams.vue
index 15b7ca1f..b7072bb8 100644
--- a/components/match/MatchLiveStreams.vue
+++ b/components/match/MatchLiveStreams.vue
@@ -421,7 +421,23 @@ export default {
       form: useForm({
         validationSchema: toTypedSchema(
           z.object({
-            link: z.string().url(),
+            link: z
+              .string()
+              .url()
+              // z.url() accepts javascript:/data: URIs (they are valid URLs);
+              // restrict to http(s) so a stored link can never become a script
+              // sink in the embed iframe or window.open.
+              .refine(
+                (value) => {
+                  try {
+                    const protocol = new URL(value).protocol;
+                    return protocol === "http:" || protocol === "https:";
+                  } catch {
+                    return false;
+                  }
+                },
+                { message: "Link must be an http(s) URL" },
+              ),
             title: z.string(),
           }),
         ),
@@ -618,7 +634,17 @@ export default {
       }
     },
     openStream(link) {
-      window.open(link, "_blank");
+      // Guard the scheme even though input validation restricts it: stored
+      // rows predate the validation and could still hold a javascript: link.
+      try {
+        const protocol = new URL(link).protocol;
+        if (protocol !== "http:" && protocol !== "https:") {
+          return;
+        }
+      } catch {
+        return;
+      }
+      window.open(link, "_blank", "noopener,noreferrer");
     },
     openEditModal(stream) {
       // ensure add modal is closed to avoid shared form conflicts
diff --git a/components/match/Replay3DLite.vue b/components/match/Replay3DLite.vue
index ccdc865e..8752d1e9 100644
--- a/components/match/Replay3DLite.vue
+++ b/components/match/Replay3DLite.vue
@@ -293,14 +293,17 @@ onMounted(() => {
       downY = e.clientY;
     }
   });
-  addEventListener("pointerup", (e) => {
-    if ((e as PointerEvent).pointerType === "touch") return; // touch = OrbitControls
+  // Named so cleanup can remove them: these are on window (not el), so if they
+  // stayed anonymous they would outlive the component and their closures would
+  // pin the whole Three.js scene (camera/controls/renderer) on every remount.
+  const onPointerUp = (e: PointerEvent) => {
+    if (e.pointerType === "touch") return; // touch = OrbitControls
     el.style.cursor = "grab";
     if (e.button !== 0) return;
     rl = false;
     if (Math.hypot(e.clientX - downX, e.clientY - downY) < 5) pickUtilLine(e); // click, not drag
-  });
-  addEventListener("pointermove", (e) => {
+  };
+  const onPointerMove = (e: PointerEvent) => {
     if (!rl) return;
     const dx = e.clientX - rlx,
       dy = e.clientY - rly;
@@ -335,7 +338,9 @@ onMounted(() => {
     const pitch = Math.atan2(newOff.y, Math.hypot(newOff.x, newOff.z));
     if (Math.abs(pitch) < 1.45) off.copy(newOff);
     controls.target.copy(camera.position).add(off);
-  });
+  };
+  addEventListener("pointerup", onPointerUp);
+  addEventListener("pointermove", onPointerMove);
   let dollyAccum = 0;
   el.addEventListener(
     "wheel",
@@ -1746,6 +1751,8 @@ onMounted(() => {
     removeEventListener("keydown", onKeyDown);
     removeEventListener("keyup", onKeyUp);
     removeEventListener("blur", clearKeys);
+    removeEventListener("pointerup", onPointerUp);
+    removeEventListener("pointermove", onPointerMove);
     document.removeEventListener("visibilitychange", onVis);
   };
 });
diff --git a/components/notification/NotificationMessage.vue b/components/notification/NotificationMessage.vue
index 3718619a..d5dbed5a 100644
--- a/components/notification/NotificationMessage.vue
+++ b/components/notification/NotificationMessage.vue
@@ -1,5 +1,6 @@
 <script lang="ts">
 import { computed, defineComponent, h, resolveComponent } from "vue";
+import DOMPurify from "dompurify";
 
 function toInternalPath(href: string | undefined): string | null {
   if (!href) return null;
@@ -58,7 +59,12 @@ export default defineComponent({
     const parsed = computed(() => {
       if (typeof window === "undefined") return null;
       const container = document.createElement("div");
-      container.innerHTML = props.html;
+      // Sanitize before parsing: notification HTML is server-built and may
+      // embed user-controlled fields (team/player names, scheduling text).
+      // DOMPurify strips scripts, event-handler attributes, and javascript:
+      // URIs so the nodeToVNode rebuild below cannot reconstruct an XSS sink.
+      // Mirrors the news components, which sanitize the same way.
+      container.innerHTML = DOMPurify.sanitize(props.html);
       return Array.from(container.childNodes)
         .map((n) => nodeToVNode(n, NuxtLink))
         .filter((c) => c !== null && c !== "");
@@ -66,7 +72,9 @@ export default defineComponent({
 
     return () => {
       if (!parsed.value) {
-        return h("span", { innerHTML: props.html });
+        // SSR (no DOM to sanitize against): render as escaped text rather than
+        // raw innerHTML. The client re-renders the sanitized markup on hydrate.
+        return h("span", props.html);
       }
       return h("span", parsed.value);
     };
diff --git a/composables/useDemoPlayback.ts b/composables/useDemoPlayback.ts
index f4c194e5..28a7b216 100644
--- a/composables/useDemoPlayback.ts
+++ b/composables/useDemoPlayback.ts
@@ -9,13 +9,21 @@ import { useNuxtApp } from "#app";
 import getGraphqlClient from "~/graphql/getGraphqlClient";
 import { useSubscriptionManager } from "~/composables/useSubscriptionManager";
 import socket from "~/web-sockets/Socket";
+import { getCurrentScope, onScopeDispose } from "vue";
 
 // Module-level so multiple useDemoPlayback() callers share one poll
 // loop instead of multiplying the request rate per mount.
 let statePollTimer: ReturnType<typeof setInterval> | null = null;
 let stateSocketHandler: ((data: any) => void) | null = null;
+// The visibilitychange listener is also shared (module-level) so any caller's
+// stopStatePoll fully tears it down; startStatePoll re-registers it once.
+let visibilityHandler: (() => void) | null = null;
 // Wall clock of the last pod-pushed state frame; gates the fallback poll.
 let lastStatePushMs = 0;
+// How many mounted callers currently hold this composable. The shared poll /
+// socket / listener are only torn down when the last one unmounts, so a child
+// component unmounting does not kill polling for a still-mounted parent.
+let activeConsumers = 0;
 
 type DemoSpecSlot = {
   slot: number;
@@ -103,6 +111,20 @@ export function useDemoPlayback() {
   const { $apollo } = useNuxtApp();
   const { subscribe, unsubscribe } = useSubscriptionManager();
 
+  // Tie the shared poll/socket/listener lifetime to the mounted callers. Without
+  // this, unmounting a component that started playback (notably dev attach mode,
+  // which never routes through stop()) left the 1Hz timer, the socket handler,
+  // and the document visibilitychange listener running forever.
+  if (getCurrentScope()) {
+    activeConsumers++;
+    onScopeDispose(() => {
+      activeConsumers = Math.max(0, activeConsumers - 1);
+      if (activeConsumers === 0) {
+        stopStatePoll();
+      }
+    });
+  }
+
   function subscriptionKey(sessionId: string) {
     return `demo-session:${sessionId}`;
   }
@@ -111,7 +133,6 @@ export function useDemoPlayback() {
   // to this socket. The timer below is a fallback poll that only sends
   // when pushes go quiet (e.g. an older pod image).
   const PUSH_FRESH_MS = 3_500;
-  let visibilityHandler: (() => void) | null = null;
   function tickOnce() {
     if (!store.matchMapId) return;
     if (Date.now() - lastStatePushMs < PUSH_FRESH_MS) return;