Cross-site scripting (XSS) vulnerability in the API pretty-printing mode in MediaWiki 1.8.0 through 1.8.4, 1.9.0 through 1.9.3, 1.10.0 through 1.10.1, and the 1.11 development versions before 1.11.0 allows remote attackers to inject arbitrary web script or HTML via unspecified vectors.