MediaWiki Improper Neutralization of Input During Web Page Generation (Cross-site Scripting) Vulnerability - CVE-2012-4378
Multiple cross-site scripting (XSS) vulnerabilities in MediaWiki before 1.18.5 and 1.19.x before 1.19.2 when unspecified JavaScript gadgets are used allow remote attackers to inject arbitrary web script or HTML via the userlang parameter to w/index.php.