Manual:$wgVerifyMimeTypeIE

MIME types: $wgVerifyMimeTypeIE
Determines whether extra checks for Internet Explorer type detection should be applied.
Introduced in version:1.34.0 (Gerrit change 487527; git #2e833876)
Removed in version:1.40.0 (Gerrit change 802592; git #005d20e4)
Allowed values:(boolean)
Default value:true

Details

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This is a conservative check for exactly what Internet Explorer 6 or so checked for, and should not trigger on, for instance, JPEG files containing links in EXIF metadata.