diff --git a/packages/docusaurus-utils/src/__tests__/index.test.ts b/packages/docusaurus-utils/src/__tests__/index.test.ts
index b8ead90d5f..f6a0543207 100644
--- a/packages/docusaurus-utils/src/__tests__/index.test.ts
+++ b/packages/docusaurus-utils/src/__tests__/index.test.ts
@@ -18,6 +18,7 @@ import {
   objectWithKeySorted,
   aliasedSitePath,
   createExcerpt,
+  isValidPathname,
 } from '../index';
 
 describe('load utils', () => {
@@ -363,4 +364,20 @@ describe('load utils', () => {
       expect(createExcerpt(testCase.input)).toEqual(testCase.output);
     });
   });
+
+  test('isValidPathname', () => {
+    expect(isValidPathname('/')).toBe(true);
+    expect(isValidPathname('/hey')).toBe(true);
+    expect(isValidPathname('/hey/ho')).toBe(true);
+    expect(isValidPathname('/hey/ho/')).toBe(true);
+    expect(isValidPathname('/hey/h%C3%B4/')).toBe(true);
+    expect(isValidPathname('/hey///ho///')).toBe(true); // Unexpected but valid
+    //
+    expect(isValidPathname('')).toBe(false);
+    expect(isValidPathname('hey')).toBe(false);
+    expect(isValidPathname('/hey/hô')).toBe(false);
+    expect(isValidPathname('/hey?qs=ho')).toBe(false);
+    expect(isValidPathname('https://fb.com/hey')).toBe(false);
+    expect(isValidPathname('//hey')).toBe(false);
+  });
 });
diff --git a/packages/docusaurus-utils/src/index.ts b/packages/docusaurus-utils/src/index.ts
index 39879cbb07..8ecc4f9f9f 100644
--- a/packages/docusaurus-utils/src/index.ts
+++ b/packages/docusaurus-utils/src/index.ts
@@ -12,6 +12,7 @@ import camelCase from 'lodash.camelcase';
 import kebabCase from 'lodash.kebabcase';
 import escapeStringRegexp from 'escape-string-regexp';
 import fs from 'fs-extra';
+import {URL} from 'url';
 
 const fileHash = new Map();
 export async function generate(
@@ -327,3 +328,14 @@ export function getEditUrl(fileRelativePath: string, editUrl?: string) {
     ? normalizeUrl([editUrl, posixPath(fileRelativePath)])
     : undefined;
 }
+
+export function isValidPathname(str: string): boolean {
+  if (!str.startsWith('/')) {
+    return false;
+  }
+  try {
+    return new URL(str, 'https://domain.com').pathname === str;
+  } catch (e) {
+    return false;
+  }
+}