WWBN AVideo is an open source video platform. In versions up to and including 26.0, a sanitization order-of-operations flaw in the user profile "about" field allows any registered user to inject arbitrary JavaScript that executes when other users visit their channel page. The `xss_esc()` function entity-encodes input before `strip_specific_tags()` can match dangerous HTML tags, and `html_entity_decode()` on output reverses the encoding, restoring the raw malicious HTML. Commit 7cfdc380dae1e56bbb5de581470d9e9957445df0 contains a patch.
Affected: Packagist: wwbn/avideo
## Summary
A sanitization order-of-operations flaw in the user profile "about" field allows any registered user to inject arbitrary JavaScript that executes when other users visit their channel page. The `xss_esc()` function entity-encodes input before `strip_specific_tags()` can match dangerous HTML tags, and `html_entity_decode()` on output reverses the encoding, restoring the raw malicious HTML.
## Details
**Input sanitization** in `objects/user.php:156`:
```php public function setAbout($about) { $this->about = strip_specific_tags(xss_esc($about)); } ```
The call order is `strip_specific_tags(xss_esc($about))`. The inner `xss_esc()` function (`objects/functionsSecurity.php:233`) calls `htmlspecialchars()`:
```php $result = @htmlspecialchars($text, ENT_QUOTES, 'UTF-8'); ```
This encodes `<script>alert(1)</script>` to `<script>alert(1)</script>`.
Then `strip_specific_tags()` (`objects/functions.php:6623-6636`) runs regex patterns to remove dangerous tags:
```php $string = preg_replace('/<' . $tag . '[^>]*>(.*?)<\/' . $tag . '>/s', $replacement, $string); ```
But the regex looks for literal `<script>` — it can never match the entity-encoded `<script>`. The sanitizer is completely neutralized by the encoding that precedes it.
**Output** in `view/channelBody.php:239-246`:
```php $about = html_entity_decode($user->getAbout()); if (!empty($advancedCustomUser->showAllAboutTextOnChannel)) { echo $about; } else { ?> <div id="aboutAreaPreCon…