When outputting user-supplied data Drupal strips potentially dangerous HTML attributes and tags or escapes characters which have a special meaning in HTML. This output filtering secures the site against cross site scripting attacks via user input.
Certain byte sequences that are valid in the UTF-8 specification are potentially dangerous when interpreted as UTF-7. Internet Explorer 6 and 7 may decode these characters as UTF-7 if they appear before the tag that specifies the page content as UTF-8, despite the fact that Drupal also sends a real HTTP header specifying the content as UTF-8. This behaviour enables malicious users to insert and execute Javascript in the context of the website if site visitors are allowed to post content.
https://drupal.org/node/449078
This vulnerability affects the following application versions:
- Drupal 6.0
- Drupal 6.1
- Drupal 6.2
- Drupal 6.3
- Drupal 6.4
- Drupal 6.5
- Drupal 6.6
- Drupal 6.7
- Drupal 6.8
- Drupal 6.9
- Drupal 6.10
- Drupal 6.11