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Introduction

In early 2025, a serious vulnerability—CVE-2025-26683—was discovered in Azure Playwright, Microsoft's cloud environment for end-to-end testing. This flaw allows an unauthorized attacker to gain elevated privileges over a network due to improper authorization checks. In this post, we will break down the issue, see how the exploit works (with code snippets), and discuss mitigation steps. For those managing tests or CI/CD in Azure, this is a must-read.

What is Azure Playwright?

Playwright is a popular Node.js library to automate Chromium, Firefox, and WebKit browsers. Many teams run Playwright tests in the cloud, and Azure Playwright offers ready-made infrastructure for this, including integrations with authentication, storage, and network controls.

Severity: High (CVSS 8.7)

- Scope: Unauthorized attacker can gain privileges over a network in Azure Playwright test runs by bypassing access controls.

How Does it Happen?

Azure Playwright uses managed identities and access tokens to secure workflow actions. However, a flawed endpoint in the Playwright runner fails to validate the user's permissions before letting them assign roles or access test artifacts.

Proof of Concept (PoC): Simple Exploitation

To make things clear, here’s a minimal code example that simulates the attack. DO NOT run this on production!

Suppose there’s a REST endpoint like this

// Node.js Express pseudo-code
app.post('/assign-role', async (req, res) => {
  const { userId, role } = req.body;
  // Oops! No proper authorization check here!
  await assignRoleToUser(userId, role); 
  res.json({ status: 'Role assigned' });
});

A malicious user can POST directly

curl -X POST https://azure-playwright-company123.cloud/api/assign-role \
 -d '{"userId":"attackerID", "role":"admin"}'

If the endpoint lacks a check for the current user's permission, the attacker becomes an admin!

Deeper Exploit Flow

Let’s say Azure Playwright uses Azure Active Directory for access control. An attacker might:

Monitor API calls: Using a proxy to see what endpoints assign roles or access artifacts.

2. Capture or fabricate a low-privilege token: (Azure tokens can easily be obtained by signing up for a free test account).
3. Replay or tamper requests: Use tools like Burp Suite or Postman to change role assignments or attempt to read/write test results.

Original References

- NVD entry for CVE-2025-26683
- Official Microsoft Azure Playwright documentation
- Example Playwright security best practices

How to Fix It?

Patch:
Update to the latest version of Azure Playwright runner. Microsoft has addressed the issue starting with version 2025.4.2.

Always validate the authenticated user's role server-side before any sensitive operation.

- Use Azure RBAC and assign only the least privileges necessary.

Best Practice Example

app.post('/assign-role', async (req, res) => {
  if (!req.user || req.user.role !== 'admin') {
    return res.status(403).json({ error: 'Forbidden' });
  }
  const { userId, role } = req.body;
  await assignRoleToUser(userId, role);
  res.json({ status: 'Role assigned' });
});

Closing Thoughts

CVE-2025-26683 is a strong reminder: in cloud services like Azure, even small authorization mistakes can cause massive privilege escalations. Review all endpoints for proper checks, keep your dependencies updated, and never assume “internal” means “secure by default.”

Stay safe, and patch today!

*Have questions or insights on this issue? Join the discussion on the Microsoft Security Response Center blog.*

Timeline

Published on: 03/31/2025 22:15:18 UTC
Last modified on: 04/30/2025 17:14:48 UTC