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EUVD-2026-364975

fkie_cve-2026-52774

YesWiki is a wiki system written in PHP. Prior to version 4.6.6, YesWiki's Bazar widget handler reflects the id GET parameter into HTML attributes using strip_tags() only. Because strip_tags() does not escape double quotes, an attacker can break out of the attribute value, inject an event handler such as onmouseover, and execute arbitrary JavaScript in the victim's browser. This issue is reachable without authentication. During validation, the vulnerable widget route returned the injected HTML for both /HomePage/widget?id=... and /NoSuchPage/widget?id=..., which shows that no login, no page ownership, no edit rights, and not even a valid page tag were required. The only routing prerequisite observed was that the Bazar extension is enabled and the request includes an id parameter. This issue has been patched in version 4.6.6.

GHSA-r5xw-gcgw-hwp5 — YesWiki Vulnerable to Reflected XSS via Unescaped `id` Parameter in Bazar Widget HTML Attributes

Affected: Packagist: yeswiki/yeswiki

### Summary YesWiki's Bazar widget handler reflects the `id` `GET` parameter into HTML attributes using `strip_tags()` only. Because `strip_tags()` does not escape double quotes, an attacker can break out of the attribute value, inject an event handler such as `onmouseover`, and execute arbitrary JavaScript in the victim's browser.

This issue is reachable without authentication. During validation, the vulnerable `widget` route returned the injected HTML for both `/HomePage/widget?id=...` and `/NoSuchPage/widget?id=...`, which shows that no login, no page ownership, no edit rights, and not even a valid page tag were required. The only routing prerequisite observed was that the Bazar extension is enabled and the request includes an `id` parameter.

### Details The primary sink is in `tools/bazar/presentation/templates/widget.tpl.html` around lines `4-7`, where `$_GET['id']` is inserted into the `data-formid` attribute:

```php data-formid="<?php echo strip_tags($_GET['id']); ?>" ```

`strip_tags()` is not an output-encoding function. It removes HTML tags, but it does not escape characters such as double quotes, so an attacker can terminate the `data-formid` attribute and inject new attacker-controlled attributes.

The route is served by `tools/bazar/handlers/__WidgetHandler.php` around lines `14-26`, which only checks whether `$_GET['id']` is present:

```php if (!isset($_GET['id'])) { return null; } ```

No `HasAccess('read')`, `HasAccess('write')`, or authentication che…