diff --git a/.changeset/itchy-scissors-suffer.md b/.changeset/itchy-scissors-suffer.md
new file mode 100644
index 000000000000..096868f5fc8f
--- /dev/null
+++ b/.changeset/itchy-scissors-suffer.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-node': patch
+---
+
+fix: return 400 response if request construction fails
diff --git a/packages/adapter-node/src/handler.js b/packages/adapter-node/src/handler.js
index d73b1c874831..5586e5169622 100644
--- a/packages/adapter-node/src/handler.js
+++ b/packages/adapter-node/src/handler.js
@@ -90,11 +90,20 @@ function serve_prerendered() {
 
 /** @type {import('polka').Middleware} */
 const ssr = async (req, res) => {
-	const request = await getRequest({
-		base: origin || get_origin(req.headers),
-		request: req,
-		bodySizeLimit: body_size_limit
-	});
+	/** @type {Request} */
+	let request;
+
+	try {
+		request = await getRequest({
+			base: origin || get_origin(req.headers),
+			request: req,
+			bodySizeLimit: body_size_limit
+		});
+	} catch {
+		res.statusCode = 400;
+		res.end('Bad Request');
+		return;
+	}
 
 	setResponse(
 		res,