Cross-site scripting (XSS) vulnerability in the formatHTML function in includes/api/ApiFormatBase.php in MediaWiki before 1.19.12, 1.20.x and 1.21.x before 1.21.6, and 1.22.x before 1.22.3 allows remote attackers to inject arbitrary web script or HTML via a crafted string located after http:// in the text parameter to api.php.

MediaWiki 1.22.x before 1.22.2, 1.21.x before 1.21.5, and 1.19.x before 1.19.11, when DjVu or PDF file upload support is enabled, allows remote attackers to execute arbitrary commands via shell metacharacters in (1) the page parameter to includes/media/DjVu.php; (2) the w parameter (aka width field) to thumb.php, which is not properly handled by includes/media/PdfHandler_body.php; and possibly unspecified vectors in (3) includes/media/Bitmap.php and (4) includes/media/ImageHandler.php.