WWBN AVideo: Stored XSS via unescaped Gallery category description

Summary

AVideo stores category descriptions from user input and later renders category_description as raw HTML in the Gallery view. A user who can create or edit
categories can store JavaScript in a category description, which executes when another user views the affected Gallery/category page.

This is a stored XSS in the category description field, separate from previously fixed XSS issues in video titles or comments.

### Details

Source:

objects/categoryAddNew.json.php

```php
$objCat->setDescription($_POST['description']);

Storage setter:

objects/category.php

public function setDescription($description)
{
$this->description = $description;
}

  Sink:

  `plugin/Gallery/view/mainAreaCategory.php`

<div id="categoryDescription<?php echo $duid; ?>" style="display: none;"><?php echo $videos[0]['category_description']; ?></div>

  The value is rendered without `htmlspecialchars()`, `htmlentities()`, `HTMLPurifier`, or equivalent output encoding.

  ### PoC

  Prerequisites:

  - AVideo current master / v29.0
  - User account with permission to create or edit categories
  - Gallery plugin/view enabled
  - At least one video assigned to the affected category

  Steps:

  1. Log in as a user who can create or edit categories.
  2. Create or edit a category.
  3. Set the category description to:

<img src=x onerror=alert(document.domain)>

  4. Save the category.
  5. Assign at least one video to that category.
  6. Open the Gallery/category page that renders the category section.
  7. The payload is inserted into the page as raw HTML and JavaScript executes.

  ### Impact

  An attacker with category edit permission can execute JavaScript in the browser of users or administrators who view the affected Gallery/category page. This can
  be used to perform actions as the victim, steal same-origin data accessible to JavaScript, or abuse administrative UI actions if an administrator views the
  malicious category.

### Recommended fix

- Sanitize category descriptions on input with the same HTML policy used for video descriptions, or store plain text only.
- Encode on output:

```php
echo htmlspecialchars($videos[0]['category_description'], ENT_QUOTES, 'UTF-8');

• If limited HTML is intended, run the description through HTMLPurifier before storage or before render.
• Add regression tests for category description rendering in Gallery views.