diff --git a/packages/playwright-core/src/mcp/browser/config.ts b/packages/playwright-core/src/mcp/browser/config.ts
index 2ecbf7acbd791..0491cec075ced 100644
--- a/packages/playwright-core/src/mcp/browser/config.ts
+++ b/packages/playwright-core/src/mcp/browser/config.ts
@@ -521,7 +521,11 @@ export function headerParser(arg: string | undefined, previous?: Record<string,
   if (!arg)
     return previous || {};
   const result: Record<string, string> = previous || {};
-  const [name, value] = arg.split(':').map(v => v.trim());
+  const colonIndex = arg.indexOf(':');
+  if (colonIndex === -1)
+    return result;
+  const name = arg.substring(0, colonIndex).trim();
+  const value = arg.substring(colonIndex + 1).trim();
   result[name] = value;
   return result;
 }
diff --git a/tests/mcp/cdp.spec.ts b/tests/mcp/cdp.spec.ts
index f05ea7c306421..d8483511fdac1 100644
--- a/tests/mcp/cdp.spec.ts
+++ b/tests/mcp/cdp.spec.ts
@@ -110,3 +110,21 @@ test('cdp server with headers', async ({ startClient, server }) => {
   });
   expect(authHeader).toBe('Bearer 1234567890');
 });
+
+test('cdp server with headers containing colons', async ({ startClient, server }) => {
+  // Regression test for https://github.com/microsoft/playwright-mcp/issues/1417
+  let customHeader = '';
+  server.setRoute('/json/version/', (req, res) => {
+    customHeader = req.headers['x-custom'];
+    res.end();
+  });
+
+  const { client } = await startClient({ args: [`--cdp-endpoint=${server.PREFIX}`, '--cdp-header', 'X-Custom: http://example.com:8080/path'] });
+  expect(await client.callTool({
+    name: 'browser_navigate',
+    arguments: { url: server.HELLO_WORLD },
+  })).toHaveResponse({
+    isError: true,
+  });
+  expect(customHeader).toBe('http://example.com:8080/path');
+});