AVideo Affected by Stored XSS via Unescaped Video Title in CDN downloadButtons.php
### Summary
WWBN/AVideo contains a stored cross-site scripting vulnerability in the CDN plugin's download buttons component. The `clean_title` field of a video record is interpolated directly into a JavaScript string literal without any escaping, allowing an attacker who can create or modify a video to inject arbitrary JavaScript that executes in the browser of any user who visits the affected download page.
### Details
At line 59 of the affected file, the following PHP code constructs a JavaScript function call:
```php
downloadURLOrAlertError(url, {}, '<?php echo $video['clean_title']; ?>.' + format, progress);
```
The `clean_title` value is echoed verbatim inside a single-quoted JavaScript string literal. No JavaScript-context escaping is applied, such as wrapping with `json_encode` or htmlspecialchars with appropriate flags. Because the value sits inside a JS string delimited by single quotes, any input containing a single quote character allows an attacker to terminate the string prematurely and inject arbitrary JavaScript expressions. The `clean_title` field is derived from user-supplied video title input, meaning any user with video creation or editing privileges can craft a malicious title. The injected script executes in the security context of whatever user loads the download page for that video, which may include administrators or authenticated users with elevated privileges.
### PoC
```python
import requests
target = "
https://example.com"
login_url = f"{target}/user"
upload_url = f"{target}/video/addNew"
session = requests.Session()
session.post(login_url, data={
"user[user]": "attacker",
"user[pass]": "attackerpassword"
})
malicious_title = "');alert(document.cookie);//"
session.post(upload_url, data={
"title": malicious_title,
"description": "poc"
})
```
After the video is created, navigate to:
```
https://example.com/plugin/CDN/downloadButtons.php?videos_id=<TARGET_VIDEO_ID>
```
The rendered page will contain:
```javascript
downloadURLOrAlertError(url, {}, '');alert(document.cookie);//.' + format, progress);
```
### Impact
Any user who can create or edit a video can store malicious JavaScript that will execute in the browser of any other user who visits the download page for that video. This includes scenarios where an attacker with a low-privilege account targets administrator sessions. Successful exploitation enables session cookie theft, credential harvesting, and actions performed on behalf of the victim within the application. Because the payload is stored server-side and triggers without further attacker interaction, all users who access download pages for attacker-controlled videos are at risk.