Ajax: Mitigate possible XSS vulnerability

Fixes gh-2432

src/ajax.js

@@ -221,14 +221,19 @@ function ajaxConvert( s, response, jqXHR, isSuccess ) {
 
 		if ( current ) {
 
-		// There's only work to do if current dataType is non-auto
+			// There's only work to do if current dataType is non-auto
 			if ( current === "*" ) {
 
 				current = prev;
 
 			// Convert response if prev dataType is non-auto and differs from current
 			} else if ( prev !== "*" && prev !== current ) {
 
+				// Mitigate possible XSS vulnerability (gh-2432)
+				if ( s.crossDomain && current === "script" ) {
+					continue;
+				}
+
 				// Seek a direct converter
 				conv = converters[ prev + " " + current ] || converters[ "* " + current ];
 

test/unit/ajax.js

@@ -71,6 +71,54 @@ QUnit.module( "ajax", {
 		};
 	} );
 
+	ajaxTest( "jQuery.ajax() - do not execute js (crossOrigin)", 2, function( assert ) {
+		return {
+			create: function( options ) {
+				options.crossDomain = true;
+				return jQuery.ajax( url( "data/script.php?header=ecma" ), options );
+			},
+			success: function() {
+				assert.ok( true, "success" );
+			},
+			complete: function() {
+				assert.ok( true, "complete" );
+			}
+		};
+	} );
+
+	ajaxTest( "jQuery.ajax() - execute js for crossOrigin when dataType option is provided", 3,
+		function( assert ) {
+			return {
+				create: function( options ) {
+					options.crossDomain = true;
+					options.dataType = "script";
+					return jQuery.ajax( url( "data/script.php?header=ecma" ), options );
+				},
+				success: function() {
+					assert.ok( true, "success" );
+				},
+				complete: function() {
+					assert.ok( true, "complete" );
+				}
+			};
+		}
+	);
+
+	ajaxTest( "jQuery.ajax() - do not execute js (crossOrigin)", 2, function( assert ) {
+		return {
+			create: function( options ) {
+				options.crossDomain = true;
+				return jQuery.ajax( url( "data/script.php" ), options );
+			},
+			success: function() {
+				assert.ok( true, "success" );
+			},
+			complete: function() {
+				assert.ok( true, "complete" );
+			}
+		};
+	} );
+
 	ajaxTest( "jQuery.ajax() - success callbacks (late binding)", 8, function( assert ) {
 		return {
 			setup: addGlobalEvents( "ajaxStart ajaxStop ajaxSend ajaxComplete ajaxSuccess", assert ),