Patch React2Shell RCE and harden auth, uploads and containers

- Upgrade next 16.0.3 -> 16.3.5 and react/react-dom 19.2.0 -> 19.3.0
  (CVE-2025-55182 / CVE-2025-66478 unauthenticated RCE), next-auth -> 4.24.15
- Require admin role on /api/users, /api/courses and /api/enrollments,
  which were unauthenticated
- Replace ALLOWED_ADMINS checks that allowed any signed-in user when the
  variable was empty with the role-based requireAdmin
- Sanitize upload filenames, restrict thumbnail extensions, store edited
  thumbnails in UPLOADS_DIR, tighten traversal checks in file routes
- Dockerfile: Node 22, pinned pnpm, non-root user, critical audit gate
- Compose: read-only rootfs, dropped caps, no-new-privileges, Postgres
  password from env
- Exclude .env from Docker build context; add security headers
- Deploy with git reset --hard instead of git pull
- Remove stale package-lock.json

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/api/admin/upload/finalize/route.ts

@@ -4,8 +4,7 @@ import fs from "fs";
 import path from "path";
 import { spawn } from "child_process";
 import { prisma } from "@/lib/prisma";
-import { getServerSession } from "next-auth";
-import { authOptions } from "@/lib/auth-options";
+import { requireAdmin } from "@/lib/admin-check";
 
 const UPLOADS_DIR = process.env.UPLOADS_DIR || "/uploads";
 
@@ -56,23 +55,11 @@ async function getVideoDurationFromFile(filePath: string): Promise<number | null
   });
 }
 
-async function checkAdmin() {
-  const session = await getServerSession(authOptions);
-  if (!session?.user?.email) throw { status: 401, message: "Unauthorized" };
-  const allowed = (process.env.ALLOWED_ADMINS || "")
-    .split(",")
-    .map((s) => s.trim())
-    .filter(Boolean);
-  if (allowed.length && !allowed.includes(session.user.email))
-    throw { status: 403, message: "Forbidden" };
-  return session;
-}
-
 export async function POST(req: Request) {
   try {
     console.log('[Upload/Finalize] Request received');
     
-    await checkAdmin();
+    await requireAdmin();
     
     const body = await req.json();
     const { videoId } = body;

app/api/admin/upload/route.ts

@@ -7,8 +7,7 @@ import { IncomingMessage } from "http";
 import { spawn } from "child_process";
 import formidable, { Fields, Files, File as FormidableFile } from "formidable";
 import { prisma } from "@/lib/prisma";
-import { getServerSession } from "next-auth";
-import { authOptions } from "@/lib/auth-options";
+import { requireAdmin } from "@/lib/admin-check";
 
 // For 2GB uploads over Tailscale (~10-50 Mbps), need 30-45 minutes
 export const maxDuration = 2700; // 45 minutes for very large uploads over slow connections
@@ -20,6 +19,8 @@ const UPLOADS_DIR = process.env.UPLOADS_DIR || "/uploads";
 // post-parse rename is a cheap atomic move instead of a multi-GB copy
 const TMP_DIR = path.join(UPLOADS_DIR, "tmp");
 
+const THUMBNAIL_EXTS = new Set([".jpg", ".jpeg", ".png", ".webp", ".gif"]);
+
 // Helper to extract video duration using FFprobe
 async function getVideoDurationFromFile(filePath: string): Promise<number | null> {
   return new Promise((resolve) => {
@@ -134,18 +135,6 @@ async function moveFile(src: string, dest: string) {
   await fs.promises.chmod(dest, 0o644);
 }
 
-async function checkAdmin() {
-  const session = await getServerSession(authOptions);
-  if (!session?.user?.email) throw { status: 401, message: "Unauthorized" };
-  const allowed = (process.env.ALLOWED_ADMINS || "")
-    .split(",")
-    .map((s) => s.trim())
-    .filter(Boolean);
-  if (allowed.length && !allowed.includes(session.user.email))
-    throw { status: 403, message: "Forbidden" };
-  return session;
-}
-
 export async function POST(req: Request) {
   // track saved paths so we can cleanup on error
   let savedVideoDest: string | undefined;
@@ -156,7 +145,7 @@ export async function POST(req: Request) {
   try {
     console.log('[Upload] Request received, content-type:', req.headers.get("content-type"));
 
-    const session = await checkAdmin();
+    const session = await requireAdmin();
 
     console.log('[Upload] Admin check passed for:', session.user?.email);
 
@@ -184,8 +173,8 @@ export async function POST(req: Request) {
     if (thumbFile) {
       try {
         const originalThumbName = thumbFile.originalFilename || path.basename(thumbFile.filepath);
-        const tExt = path.extname(originalThumbName) || ".jpg";
-        const thumbFilename = `${Date.now()}-thumb${tExt}`;
+        const tExt = path.extname(originalThumbName).toLowerCase();
+        const thumbFilename = `${Date.now()}-thumb${THUMBNAIL_EXTS.has(tExt) ? tExt : ".jpg"}`;
         const thumbDest = path.join(UPLOADS_DIR, "thumbnails", thumbFilename);
         await moveFile(thumbFile.filepath, thumbDest);
         thumbnailUrl = `/api/thumbnails/${thumbFilename}`;
@@ -198,7 +187,8 @@ export async function POST(req: Request) {
     if (!isManualCopy) {
       if (!videoFile) return NextResponse.json({ error: "no file" }, { status: 400 });
 
-      const originalFilename = videoFile.originalFilename || path.basename(videoFile.filepath);
+      // basename: the client-supplied name must not be able to contain "../"
+      const originalFilename = path.basename(videoFile.originalFilename || videoFile.filepath);
       const filename = `${Date.now()}-${originalFilename}`;
       const dest = path.join(UPLOADS_DIR, "videos", filename);