diff --git a/README.md b/README.md
index c909b05..e902dab 100644
--- a/README.md
+++ b/README.md
@@ -116,7 +116,7 @@ site. To force the raw server instead, use `npm run dev:next` (don't point a tun
 | --- | --- | --- |
 | `/api/heatmap` | `GET` | Proxies the user's contribution heatmap from `git.dvorakmortonxd.dev`. |
 | `/api/activities` | `GET` | Fetches the GitDXD activity feed and keeps only the user's own events. |
-| `/api/ping?url=…` | `GET` | Health-checks a service. Handles `minecraft://host:port` via mcstatus.io; treats any non-5xx HTTP response as "up". |
+| `/api/ping?url=…` | `GET` | Health-checks an **allow-listed** service (the site's own `*.dvorakmortonxd.dev` hosts and the friends' sites). Handles `minecraft://host:port` via mcstatus.io; treats any non-5xx response as "up". Other hosts and schemes are rejected and redirects are never followed, so it can't be used to probe the LAN (SSRF guard). |
 
 ## 📁 Project Structure
 
diff --git a/opencode.md b/opencode.md
index 7cee25a..2d335fb 100644
--- a/opencode.md
+++ b/opencode.md
@@ -83,7 +83,7 @@ src/app/
   api/
     heatmap/route.ts    → proxy for git.dvorakmortonxd.dev contribution heatmap
     activities/route.ts → proxy for the user's GitDXD activity feed
-    ping/route.ts       → service health check (HTTP + minecraft:// via mcstatus.io)
+    ping/route.ts       → service health check (HTTP + minecraft:// via mcstatus.io); host allowlist
   components/
     ThemeRoot.tsx       → picks which shell to show (the router of the UI)
     TerminalLayout.tsx  → "terminal" theme (Gruvbox)
@@ -261,6 +261,12 @@ list reordering, not free placement. Don't confuse the two.
 - The SMP service shortcut opens `SMP_APP` (in `apps.tsx`, registered in
   `APP_BY_ID` only, like `ALACRITTY_APP`) — a Minecraft-style join menu that
   reads live data from `/api/ping?url=minecraft://…`.
+- `/api/ping` is a **host-allowlisted** SSRF guard (public + unauthenticated):
+  it only contacts `*.dvorakmortonxd.dev` plus the friends' domains, rejects
+  other hosts/schemes, validates the `minecraft://` address, and never follows
+  redirects. **Adding a service or friend host means adding it to
+  `ALLOWED_HOSTS` in `api/ping/route.ts`**, otherwise its status dot reads
+  "Dead". Do not turn this route back into an open fetch proxy.
 - Service shortcuts show the real site in an iframe via
   `createWebsiteApp({ embed: true })` (the shortcut's `embed` flag). It only
   works for sites that don't send `X-Frame-Options` / a `frame-ancestors` CSP.
diff --git a/src/app/api/ping/route.ts b/src/app/api/ping/route.ts
index c7074a3..0bc19d4 100644
--- a/src/app/api/ping/route.ts
+++ b/src/app/api/ping/route.ts
@@ -1,5 +1,34 @@
 import { NextResponse } from 'next/server';
 
+// This route is reachable without authentication and it makes the server issue
+// an outbound request for whoever calls it. Without an allowlist,
+// `?url=http://192.168.x.x` turns the site into an open SSRF gadget / LAN port
+// scanner (and an open request proxy in general). Only the site's own services,
+// the Minecraft SMP and the friends' sites are actually health-checked.
+//
+// Host matching is exact or by subdomain (e.g. anything under
+// dvorakmortonxd.dev). Keep this in sync with the ServiceButton `url`/`checkUrl`
+// values in components/apps.tsx and components/TerminalLayout.tsx, and with the
+// friend list in data.ts.
+const ALLOWED_HOSTS = [
+  'dvorakmortonxd.dev', // ai / jelly / navidrome / git / proxmox / mc (SMP)
+  'skopec.dev',
+  'bukovinafilip.com',
+  'vlcak.me',
+];
+
+function isAllowedHost(hostname: string): boolean {
+  const host = hostname.toLowerCase().replace(/\.$/, '');
+  return ALLOWED_HOSTS.some(
+    (allowed) => host === allowed || host.endsWith(`.${allowed}`)
+  );
+}
+
+// A Minecraft address we are willing to forward to mcstatus.io: a plain
+// hostname/IPv4 with an optional port. Deliberately excludes '@', '/', '?', '#'
+// and IPv6 brackets so it cannot smuggle another path into the upstream URL.
+const MINECRAFT_ADDRESS = /^[a-z0-9.-]+(:\d{1,5})?$/i;
+
 export async function GET(request: Request) {
   const { searchParams } = new URL(request.url);
   const url = searchParams.get('url');
@@ -7,7 +36,12 @@ export async function GET(request: Request) {
   if (!url) return NextResponse.json({ status: 'down' });
 
   if (url.startsWith('minecraft://')) {
-    const address = url.replace('minecraft://', '');
+    const address = url.slice('minecraft://'.length);
+    const host = MINECRAFT_ADDRESS.test(address) ? address.split(':')[0] : '';
+    if (!host || !isAllowedHost(host)) {
+      return NextResponse.json({ status: 'down' });
+    }
+
     try {
       // mcsrvstat.us is unreliable at resolving some hostnames, so use mcstatus.io.
       const res = await fetch(`https://api.mcstatus.io/v2/status/java/${address}`, {
@@ -30,18 +64,38 @@ export async function GET(request: Request) {
     }
   }
 
+  let target: URL;
   try {
-    const httpRes = await fetch(url, {
+    target = new URL(url);
+  } catch {
+    return NextResponse.json({ status: 'down' });
+  }
+
+  // Only allow-listed http(s) hosts. This rejects file:, ftp:, internal IPs,
+  // `user@host` tricks and anything the allowlist does not cover.
+  if (
+    (target.protocol !== 'http:' && target.protocol !== 'https:') ||
+    !isAllowedHost(target.hostname)
+  ) {
+    return NextResponse.json({ status: 'down' });
+  }
+
+  try {
+    const httpRes = await fetch(target, {
       method: 'GET',
-      signal: AbortSignal.timeout(5000)
+      // Never follow redirects: an allowed host could otherwise redirect to an
+      // internal address and reopen the SSRF. A 3xx still means the service
+      // answered, so it counts as "up".
+      redirect: 'manual',
+      signal: AbortSignal.timeout(5000),
     });
 
     // Accept all non-5xx responses as "up". 5xx usually means origin or gateway errors (like Cloudflare 521, 522, etc.)
     if (httpRes && httpRes.status < 500) {
       return NextResponse.json({ status: 'up' });
     }
-  } catch (e) {
-    console.error(`Failed to ping ${url}`, e);
+  } catch {
+    // Request failed or timed out; fall through to "down".
   }
 
   return NextResponse.json({ status: 'down' });