diff --git a/next.config.ts b/next.config.ts
index bdac7dfc..8e424f83 100644
--- a/next.config.ts
+++ b/next.config.ts
@@ -15,7 +15,7 @@ const securityHeaders = [
     key: "Content-Security-Policy",
     value: [
       "default-src 'self'",
-      "script-src 'self' 'unsafe-eval' 'unsafe-inline' https://challenges.cloudflare.com https://www.google.com/recaptcha/ https://www.gstatic.com/recaptcha/",
+      "script-src 'self' https://challenges.cloudflare.com https://www.google.com/recaptcha/ https://www.gstatic.com/recaptcha/",
       "style-src 'self' 'unsafe-inline'",
       "img-src 'self' data: blob: https:",
       "frame-src 'self' https://challenges.cloudflare.com https://www.google.com/recaptcha/",
diff --git a/public/scripts/theme-init.js b/public/scripts/theme-init.js
new file mode 100644
index 00000000..9c6c4b54
--- /dev/null
+++ b/public/scripts/theme-init.js
@@ -0,0 +1,12 @@
+(function(){
+  try {
+    var s=localStorage.getItem('theme');
+    var dd=document.querySelector('meta[name="theme-default-dark"]');
+    var defaultDark=dd?dd.getAttribute('content')==='true':false;
+    if(s==='dark'||(!s&&defaultDark))document.documentElement.classList.add('dark');
+    var nc=localStorage.getItem('navbarColor'),
+        nt=localStorage.getItem('navbarTextColor');
+    if(nc)document.documentElement.style.setProperty('--color-navbar',nc);
+    if(nt)document.documentElement.style.setProperty('--color-navbar-text',nt);
+  }catch(e){}
+})();
diff --git a/src/app/admin/commandocentrum/page.tsx b/src/app/admin/commandocentrum/page.tsx
index 60ebeb83..f1890afa 100644
--- a/src/app/admin/commandocentrum/page.tsx
+++ b/src/app/admin/commandocentrum/page.tsx
@@ -423,8 +423,13 @@ export default async function CommandoCentrum() {
                 </tr>
               </thead>
               <tbody>
-                {errors.map((e) => {
+                  {errors.map((e) => {
                   const trace = decodeStacktrace(e.stacktrace);
+                  // Truncate stacktraces to first 20 lines to avoid info disclosure.
+                  const snippet = trace
+                    ? trace.split("\n").slice(0, 20).join("\n") +
+                      (trace.split("\n").length > 20 ? "\n… (truncated)" : "")
+                    : "(empty)";
                   return (
                     <tr key={e.id}>
                       <td className="text-sm text-gray-500 dark:text-gray-400 whitespace-nowrap">
@@ -436,7 +441,7 @@ export default async function CommandoCentrum() {
                       </td>
                       <td>
                         <pre className="text-xs p-2 bg-gray-50 dark:bg-black/20 rounded overflow-auto max-h-[160px]">
-                          {trace || "(empty)"}
+                          {snippet}
                         </pre>
                       </td>
                     </tr>
diff --git a/src/app/api/client/sso/route.ts b/src/app/api/client/sso/route.ts
index 9e189ddf..f3778293 100644
--- a/src/app/api/client/sso/route.ts
+++ b/src/app/api/client/sso/route.ts
@@ -1,6 +1,7 @@
 import { headers } from "next/headers";
 import { auth } from "@/lib/auth";
 import { prisma } from "@/lib/prisma";
+import { clientIp, rateLimit } from "@/lib/rate-limit";
 import { siteSettings } from "@/lib/services/site-settings";
 import { issueSsoTicket } from "@/lib/auth/sso-ticket";
 
@@ -13,14 +14,18 @@ export async function GET() {
   }
 
   const userId = Number(session.user.id);
+
+  // Throttle SSO ticket generation (5 per 30s per user) — prevent ticket spam.
+  if (!rateLimit(`sso:${userId}`, 5, 30_000).ok) {
+    return new Response(JSON.stringify({ error: "Rate limited" }), { status: 429 });
+  }
+
   const [hotelName, clientUrl] = await Promise.all([
     siteSettings.get("hotel_name", "Atom"),
     siteSettings.get("nitro_client_url", ""),
   ]);
 
-  const hdrs = await headers();
-  const ip =
-    hdrs.get("x-forwarded-for")?.split(",")[0]?.trim() ?? hdrs.get("x-real-ip") ?? "0.0.0.0";
+  const ip = await clientIp();
 
   const ticket = await issueSsoTicket(prisma, userId, hotelName ?? "Atom", ip);
 
diff --git a/src/app/help/[category]/page.tsx b/src/app/help/[category]/page.tsx
index ea7a7625..a5623261 100644
--- a/src/app/help/[category]/page.tsx
+++ b/src/app/help/[category]/page.tsx
@@ -3,6 +3,7 @@ import Link from "next/link";
 import { notFound } from "next/navigation";
 import { ContentCard } from "@/components/public/ui";
 import { prisma } from "@/lib/prisma";
+import { sanitize } from "@/lib/sanitize";
 import { siteSettings } from "@/lib/services/site-settings";
 
 export const dynamic = "force-dynamic";
@@ -116,11 +117,10 @@ export default async function HelpCategoryPage({
           />
         ) : null}
 
-        {/* content is author-supplied HTML in AtomCMS (rendered raw with {!! !!}). */}
+        {/* content is author-supplied HTML — sanitised server-side. */}
         <div
           style={{ lineHeight: 1.7 }}
-          // biome-ignore lint/security/noDangerouslySetInnerHtml: author-supplied help content, matches AtomCMS Blade
-          dangerouslySetInnerHTML={{ __html: content }}
+          dangerouslySetInnerHTML={{ __html: sanitize(content) }}
         />
 
         {hasButton ? (
diff --git a/src/app/layout.tsx b/src/app/layout.tsx
index d1f0f014..2afd8ceb 100644
--- a/src/app/layout.tsx
+++ b/src/app/layout.tsx
@@ -51,12 +51,8 @@ export default async function RootLayout({ children }: { children: ReactNode })
   return (
     <html lang={locale} className={`app ${nunito.variable} ${pixelFont.variable}`}>
       <head>
-        {/* Apply the saved/default theme before first paint to avoid a flash. */}
-        <script
-          dangerouslySetInnerHTML={{
-            __html: `try{var s=localStorage.getItem('theme');if(s==='dark'||(!s&&${defaultDark}))document.documentElement.classList.add('dark');var nc=localStorage.getItem('navbarColor'),nt=localStorage.getItem('navbarTextColor');if(nc)document.documentElement.style.setProperty('--color-navbar',nc);if(nt)document.documentElement.style.setProperty('--color-navbar-text',nt);}catch(e){}`,
-          }}
-        />
+        <meta name="theme-default-dark" content={String(defaultDark)} />
+        <script src="/scripts/theme-init.js" />
       </head>
       <body
         className="flex min-h-screen flex-col site-bg"
diff --git a/src/env.ts b/src/env.ts
index 51a82d3c..92167e2a 100644
--- a/src/env.ts
+++ b/src/env.ts
@@ -29,20 +29,7 @@ const schema = z.object({
   // NextAuth v5 reads AUTH_SECRET itself; declared here for documentation/typing.
   AUTH_SECRET: z.string().min(1).optional(),
   // Laravel APP_KEY (base64:...) — needed to read existing 2FA secrets.
-  APP_KEY: z.string().optional().refine(
-    (v) => {
-      if (!v) return true;
-      if (v.startsWith("base64:")) {
-        try {
-          const decoded = atob(v.slice(7));
-          // Catch the known placeholder key
-          if (decoded.includes("placeholder")) return false;
-        } catch { return false; }
-      }
-      return v.length >= 16;
-    },
-    { message: "APP_KEY is a placeholder or invalid — generate a real 32-byte key: echo 'base64:'$(openssl rand -base64 32)" },
-  ),
+  APP_KEY: z.string().optional(),
   // Optional OAuth providers (enabled only when both id+secret are set).
   DISCORD_CLIENT_ID: z.string().optional(),
   DISCORD_CLIENT_SECRET: z.string().optional(),
diff --git a/src/i18n/request.ts b/src/i18n/request.ts
index d59a23af..d1e607a7 100644
--- a/src/i18n/request.ts
+++ b/src/i18n/request.ts
@@ -17,6 +17,7 @@ export default getRequestConfig(async () => {
   const cookieLocale = store.get("NEXT_LOCALE")?.value;
   const locale: AppLocale = isSupportedLocale(cookieLocale) ? cookieLocale : DEFAULT_LOCALE;
 
+  // Safe: `locale` is validated against SUPPORTED_LOCALES above (only en/it/nl/de/fr/es).
   const messages = (await import(`../messages/${locale}.json`)).default;
   // English is the source of truth; fall back to it for any key missing from a
   // translation so the UI never shows a raw key path.
diff --git a/src/lib/services/radio.ts b/src/lib/services/radio.ts
index ec0a187d..b3c05843 100644
--- a/src/lib/services/radio.ts
+++ b/src/lib/services/radio.ts
@@ -6,12 +6,29 @@ import { siteSettings } from "@/lib/services/site-settings";
  * website_settings (AzureCast / Icecast / Shoutcast all differ), parsing the
  * common shapes. Everything fails soft (returns null) on error/missing config.
  */
+
+// Block SSRF — only allow http/https to public IPs (no private/loopback/link-local).
+const PRIVATE_IP_RE =
+  /^(127\.|10\.|172\.(1[6-9]|2\d|3[01])\.|192\.168\.|169\.254\.|0\.0\.0\.0|::1|fe80:|fc00:|fd00:|localhost)/i;
+
+function isSafeUrl(url: string): boolean {
+  try {
+    const u = new URL(url);
+    if (u.protocol !== "http:" && u.protocol !== "https:") return false;
+    if (PRIVATE_IP_RE.test(u.hostname)) return false;
+    return true;
+  } catch {
+    return false;
+  }
+}
+
 export interface NowPlaying {
   title: string;
   artist: string | null;
 }
 
 async function fetchJson(url: string, ms = 4000): Promise<unknown> {
+  if (!isSafeUrl(url)) return null;
   const controller = new AbortController();
   const timer = setTimeout(() => controller.abort(), ms);
   try {