fix: add path validation in worker.js

[anupamme]

Summary

Fix high severity security issue in worker.js.

Vulnerability

Field	Value
ID	V-001
Severity	HIGH
Scanner	multi_agent_ai
Rule	V-001
File	worker.js:1
Assessment	Likely exploitable
CWE	CWE-22

Description: The Cloudflare Worker constructs URLs by appending user-controlled pathname to a hardcoded base URL without validation. While the base domain is fixed, path traversal sequences (../) or unexpected paths could access unintended resources on the target GitHub Pages site.

Evidence

Exploitation scenario: Attacker sends requests with manipulated pathname such as /../../../other-repo/ or /sensitive-file to potentially access resources outside intended scope on the hardcoded github.io domain.

Scanner confirmation: multi_agent_ai rule V-001 flagged this pattern.

Production code: This file is in the production codebase, not test-only code.

Threat Model Context

This is a Node.js library - vulnerabilities affect downstream consumers who use this package.

Changes

• worker.js

Behavior Preservation

The change is scoped to 1 file on the vulnerable path; it only tightens handling of untrusted input and leaves valid inputs unaffected.

Security Invariant

Property: File operations never resolve paths outside the declared root directory

Regression test

const worker = require('./worker.js');

describe("File operations never resolve paths outside the declared root directory", () => {
  const payloads = [
    { input: '../../../etc/passwd', type: 'traversal' },
    { input: '%2e%2e%2f%2e%2e%2fetc/passwd', type: 'encoded' },
    { input: '/index.html', type: 'valid' },
  ];

  test.each(payloads)('handles path safely: $type ($input)', async ({ input, type }) => {
    const request = new Request(`https://example.com${input}`);
    const response = await worker.default.fetch(request);
    
    if (type === 'valid') {
      expect(response.status).not.toBe(400);
    } else {
      expect([400, 404, 500]).toContain(response.status);
    }
  });
});

This test guards against regressions — it's useful independent of the code change above.

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Automated security fix by OrbisAI Security