Manual:$wgUseXssLanguage

Language, regional and character encoding settings: $wgUseXssLanguage
Whether to enable the x-xss language code, used to make checking for XSS issues more convenient.
Introduced in version:1.41.0 (Gerrit change 959239; git #e9991ffb)
Removed in version:Still in use
Allowed values:(boolean)
Default value:false (but true in DevelopmentSettings.php )

Details

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Whether to enable the x-xss language code, used to make checking for XSS issues more convenient.

When this feature is enabled, the language code can be selected via the ?uselang=x-xss URL parameter. In this fake language, every interface message becomes a simulated cross-site scripting attack, trying to run alert("message-key") JavaScript code; this simulates an attacker who can change individual messages (e.g. an administrator who can edit the MediaWiki namespace ). This feature does not affect parser output. If any alert is shown in the browser, then the corresponding message was not escaped correctly; either the code using the message needs to be fixed, or the message key should be added to $wgRawHtmlMessages .

This feature should never be enabled on a production wiki, but it can be very useful for development.

See also

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