diff --git a/code/lib/core-server/src/utils/__tests__/server-channel.test.ts b/code/lib/core-server/src/utils/__tests__/server-channel.test.ts
new file mode 100644
index 000000000000..786370be0f99
--- /dev/null
+++ b/code/lib/core-server/src/utils/__tests__/server-channel.test.ts
@@ -0,0 +1,86 @@
+import type { Server } from 'http';
+import { Channel } from '@storybook/channels';
+
+import { EventEmitter } from 'events';
+import { stringify } from 'telejson';
+import { getServerChannel, ServerChannelTransport } from '../get-server-channel';
+
+describe('getServerChannel', () => {
+  test('should return a channel', () => {
+    const server = { on: jest.fn() } as any as Server;
+    const result = getServerChannel(server);
+    expect(result).toBeInstanceOf(Channel);
+  });
+
+  test('should attach to the http server', () => {
+    const server = { on: jest.fn() } as any as Server;
+    getServerChannel(server);
+    expect(server.on).toHaveBeenCalledWith('upgrade', expect.any(Function));
+  });
+});
+
+describe('ServerChannelTransport', () => {
+  test('parses simple JSON', () => {
+    const server = new EventEmitter() as any as Server;
+    const socket = new EventEmitter();
+    const transport = new ServerChannelTransport(server);
+    const handler = jest.fn();
+    transport.setHandler(handler);
+
+    // @ts-expect-error (an internal API)
+    transport.socket.emit('connection', socket);
+    socket.emit('message', '"hello"');
+
+    expect(handler).toHaveBeenCalledWith('hello');
+  });
+  test('parses object JSON', () => {
+    const server = new EventEmitter() as any as Server;
+    const socket = new EventEmitter();
+    const transport = new ServerChannelTransport(server);
+    const handler = jest.fn();
+    transport.setHandler(handler);
+
+    // @ts-expect-error (an internal API)
+    transport.socket.emit('connection', socket);
+    socket.emit('message', JSON.stringify({ type: 'hello' }));
+
+    expect(handler).toHaveBeenCalledWith({ type: 'hello' });
+  });
+  test('supports telejson cyclical data', () => {
+    const server = new EventEmitter() as any as Server;
+    const socket = new EventEmitter();
+    const transport = new ServerChannelTransport(server);
+    const handler = jest.fn();
+    transport.setHandler(handler);
+
+    // @ts-expect-error (an internal API)
+    transport.socket.emit('connection', socket);
+
+    const input: any = { a: 1 };
+    input.b = input;
+    socket.emit('message', stringify(input));
+
+    expect(handler.mock.calls[0][0]).toMatchInlineSnapshot(`
+      Object {
+        "a": 1,
+        "b": [Circular],
+      }
+    `);
+  });
+  test('skips telejson classes and functions in data', () => {
+    const server = new EventEmitter() as any as Server;
+    const socket = new EventEmitter();
+    const transport = new ServerChannelTransport(server);
+    const handler = jest.fn();
+    transport.setHandler(handler);
+
+    // @ts-expect-error (an internal API)
+    transport.socket.emit('connection', socket);
+
+    const input = { a() {}, b: class {} };
+    socket.emit('message', stringify(input));
+
+    expect(handler.mock.calls[0][0].a).toEqual(expect.any(String));
+    expect(handler.mock.calls[0][0].b).toEqual(expect.any(String));
+  });
+});
diff --git a/code/lib/core-server/src/utils/get-server-channel.ts b/code/lib/core-server/src/utils/get-server-channel.ts
index c44c51b36307..1a488afb06c9 100644
--- a/code/lib/core-server/src/utils/get-server-channel.ts
+++ b/code/lib/core-server/src/utils/get-server-channel.ts
@@ -27,7 +27,10 @@ export class ServerChannelTransport {
     this.socket.on('connection', (wss) => {
       wss.on('message', (raw) => {
         const data = raw.toString();
-        const event = typeof data === 'string' && isJSON(data) ? parse(data) : data;
+        const event =
+          typeof data === 'string' && isJSON(data)
+            ? parse(data, { allowFunction: false, allowClass: false })
+            : data;
         this.handler?.(event);
       });
     });
@@ -38,7 +41,7 @@ export class ServerChannelTransport {
   }
 
   send(event: any) {
-    const data = stringify(event, { maxDepth: 15, allowFunction: true });
+    const data = stringify(event, { maxDepth: 15, allowFunction: false, allowClass: false });
 
     Array.from(this.socket.clients)
       .filter((c) => c.readyState === WebSocket.OPEN)