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.

includes/User.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 terminates validation of a user token upon encountering the first incorrect character, which makes it easier for remote attackers to obtain access via a brute-force attack that relies on timing differences in responses to incorrect token guesses.

includes/upload/UploadBase.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 does not prevent use of invalid namespaces in SVG files, which allows remote attackers to conduct cross-site scripting (XSS) attacks via an SVG upload, as demonstrated by use of a W3C XHTML namespace in conjunction with an IFRAME element.

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.

The CleanChanges extension for MediaWiki before 1.19.9, 1.20.x before 1.20.8, and 1.21.x before 1.21.3, when "Group changes by page in recent changes and watchlist" is enabled, allows remote attackers to obtain sensitive information (revision-deleted IPs) via the Recent Changes page.

Incomplete blacklist vulnerability in Sanitizer::checkCss in MediaWiki before 1.19.9, 1.20.x before 1.20.8, and 1.21.x before 1.21.3 allows remote attackers to conduct cross-site scripting (XSS) attacks via certain non-ASCII characters in CSS, as demonstrated using variations of "expression" containing (1) full width characters or (2) IPA extensions, which are converted and rendered by Internet Explorer.

Incomplete blacklist vulnerability in Sanitizer::checkCss in MediaWiki before 1.19.9, 1.20.x before 1.20.8, and 1.21.x before 1.21.3 allows remote attackers to conduct cross-site scripting (XSS) attacks via a \b (backspace) character in CSS.

Cross-site request forgery (CSRF) vulnerability in the CentralAuth extension for MediaWiki before 1.19.9, 1.20.x before 1.20.8, and 1.21.x before 1.21.3 allows remote attackers to hijack the authentication of users for requests that login via vectors involving image loading.

Cross-site scripting (XSS) vulnerability in the ZeroRatedMobileAccess extension for MediaWiki 1.19.x before 1.19.9, 1.20.x before 1.20.8, and 1.21.x before 1.21.3 allows remote attackers to inject arbitrary web script or HTML via the "to" parameter to index.php.