GitHub Security Advisory: GHSA-v9fg-3cr2-277j
Package: rustfs (RUST)
Severity: CRITICAL (CVSS 9.0)
CWE: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Vulnerable versions: < 1.0.0-alpha.83
Patched in: 1.0.0-alpha.83

Summary: Rust has Critical Stored XSS in Preview Modal, leading to Administrative Account Takeover

Details:
### Summary
A Stored Cross-Site Scripting (XSS) vulnerability in the RustFS Console allows an attacker to execute arbitrary JavaScript in the context of the management console. By bypassing the PDF preview logic, an attacker can steal administrator credentials from `localStorage`, leading to full account takeover and system compromise.

### Details
The vulnerability exists due to improper validation of the response content type during the file preview process and a lack of origin separation between the S3 object delivery and the management console.

1. **Origin of Credentials**: The RustFS Console stores highly sensitive S3 credentials (AccessKey, SecretKey, SessionToken) in the browser's `localStorage`.
   - **File**: `console/composables/useAuth.ts`
   - **Evidence**: [Lines 14](https://github.com/rustfs/console/blob/c2bd75adacad0d0182c32d5271e8ff150c4a02db/composables/useAuth.ts#L14) and [18-25](https://github.com/rustfs/console/blob/c2bd75adacad0d0182c32d5271e8ff150c4a02db/composables/useAuth.ts#L18-L25) show that credentials are held in `useLocalStorage('auth.credentials', {})` and `useLocalStorage('auth.permanent', undefined)`.
2. **Insecure Preview Implementation**: In `console/components/object/preview-modal.vue`, the application identifies a PDF file based on its extension or metadata and [renders it using an `<iframe>`](https://github.com/rustfs/console/blob/6ab024be1c49bc9549a24ed1d09348f5e7039876/components/object/preview-modal.vue#L10).
3. **Same-Origin Vulnerability**: RustFS typically hosts the management console and the S3 API on the same origin (e.g., the same IP and port). 
4. **Bypass Attack**: An attacker can upload a file named `xss.pdf` but set its `Content-Type` metadata to `text/html`. Because the `iframe` is hosted on the same origin as the console, the executed script has unrestricted access to the parent window's `localStorage`.

### PoC
<img width="6006" height="3096" alt="CleanShot 2026-02-01 at 18 36 54@2x" src="https://github.com/user-attachments/assets/f2f5dae6-1e19-4133-9a69-f7d8ec604dad" />

This PoC demonstrates how to steal a victim's administrative credentials by tricking them into previewing a malicious file.

**1. Create the malicious payload (`xss.html`):**
```html
<script>
  alert('XSS Success!\nLocalStorage Data: ' + JSON.stringify(window.parent.localStorage));
</script>
```

**2. Setup the environment and upload the payload:**
```bash
# 1. Create a target bucket
mc mb rustfs/my-bucket

# 2. Upload the HTML file as a PDF with HTML content type
mc cp xss.html rustfs/my-bucket/xss.pdf --attr "Content-Type=text/html"
```

**3. Trigger the vulnerability:**
1. Login to the RustFS Console as an administrator.
2. Navigate to `my-bucket`.
3. Click the "Preview" button for the `xss.pdf` file.
4. The JavaScript executes, demonstrating access to the administrative session data.

### Impact
- **Character**: Stored Cross-Site Scripting (XSS).
- **Target**: System Administrators using the Console.
- **Result**: Full Ac