An issue was discovered in ApiPageSet.php in MediaWiki before 1.35.12, 1.36.x through 1.39.x before 1.39.5, and 1.40.x before 1.40.1. It allows attackers to cause a denial of service (unbounded loop and RequestTimeoutException) when querying pages redirected to other variants with redirects and converttitles set.

Mediawiki v1.40.0 does not validate namespaces used in XML files. Therefore, if the instance administrator allows XML file uploads, a remote attacker with a low-privileged user account can use this exploit to become an administrator by sending a malicious link to the instance administrator.

An issue was discovered in MediaWiki before 1.35.11, 1.36.x through 1.38.x before 1.38.7, 1.39.x before 1.39.4, and 1.40.x before 1.40.1. It is possible to bypass the Bad image list (aka badFile) by using the thumb parameter (aka Manualthumb) of the File syntax.

Cross-site scripting (XSS) vulnerability in includes/actions/InfoAction.php in MediaWiki before 1.21.9 and 1.22.x before 1.22.6 allows remote attackers to inject arbitrary web script or HTML via the sort key in an info action.

Cross-site scripting (XSS) vulnerability in the outputPage function in includes/SkinTemplate.php in MediaWiki before 1.17.5, 1.18.x before 1.18.4, and 1.19.x before 1.19.1 allows remote attackers to inject arbitrary web script or HTML via the uselang parameter to index.php/Main_page.

includes/User.php in MediaWiki before 1.16.5, when wgBlockDisablesLogin is enabled, does not clear certain cached data after verification of an auth token fails, which allows remote attackers to bypass authentication by creating crafted wikiUserID and wikiUserName cookies, or by leveraging an unattended workstation.

Cross-site scripting (XSS) vulnerability in MediaWiki before 1.16.5, when Internet Explorer 6 or earlier is used, allows remote attackers to inject arbitrary web script or HTML via an uploaded file accessed with a dangerous extension such as .shtml at the end of the query string, in conjunction with a modified URI path that has a %2E sequence in place of the . (dot) character. NOTE: this vulnerability exists because of an incomplete fix for CVE-2011-1578 and CVE-2011-1587.

Cross-site scripting (XSS) vulnerability in MediaWiki before 1.16.3, when Internet Explorer 6 or earlier is used, allows remote attackers to inject arbitrary web script or HTML via an uploaded file accessed with a dangerous extension such as .html at the end of the query string, in conjunction with a modified URI path that has a %2E sequence in place of the . (dot) character.

Cross-site scripting (XSS) vulnerability in MediaWiki before 1.16.4, when Internet Explorer 6 or earlier is used, allows remote attackers to inject arbitrary web script or HTML via an uploaded file accessed with a dangerous extension such as .html located before a ? (question mark) in a query string, in conjunction with a modified URI path that has a %2E sequence in place of the . (dot) character. NOTE: this vulnerability exists because of an incomplete fix for CVE-2011-1578.

api.php in MediaWiki before 1.15.5 does not prevent use of public caching headers for private data, which allows remote attackers to bypass intended access restrictions and obtain sensitive information by retrieving documents from an HTTP proxy cache that has been used by a victim.