diff --git a/src/wp-includes/kses.php b/src/wp-includes/kses.php
index 8cc521346a..964ef7fd6e 100644
--- a/src/wp-includes/kses.php
+++ b/src/wp-includes/kses.php
@@ -1985,9 +1985,7 @@ function safecss_filter_attr( $css, $deprecated = '' ) {
 	$css = wp_kses_no_null( $css );
 	$css = str_replace( array( "\n", "\r", "\t" ), '', $css );
 
-	if ( preg_match( '%[\\\\(&=}]|/\*%', $css ) ) { // remove any inline css containing \ ( & } = or comments
-		return '';
-	}
+	$allowed_protocols = wp_allowed_protocols();
 
 	$css_array = explode( ';', trim( $css ) );
 
@@ -1998,6 +1996,7 @@ function safecss_filter_attr( $css, $deprecated = '' ) {
 	 * @since 4.4.0 Added support for `min-height`, `max-height`, `min-width`, and `max-width`.
 	 * @since 4.6.0 Added support for `list-style-type`.
 	 * @since 5.0.0 Added support for `text-transform`.
+	 * @since 5.0.0 Added support for `background-image`.
 	 *
 	 * @param string[] $attr Array of allowed CSS attributes.
 	 */
@@ -2006,6 +2005,7 @@ function safecss_filter_attr( $css, $deprecated = '' ) {
 		array(
 			'background',
 			'background-color',
+			'background-image',
 
 			'border',
 			'border-width',
@@ -2076,6 +2076,24 @@ function safecss_filter_attr( $css, $deprecated = '' ) {
 		)
 	);
 
+	/*
+	 * CSS attributes that accept URL data types.
+	 *
+	 * This is in accordance to the CSS spec and unrelated to
+	 * the sub-set of supported attributes above.
+	 *
+	 * See: https://developer.mozilla.org/en-US/docs/Web/CSS/url
+	 */
+	$css_url_data_types = array(
+		'background',
+		'background-image',
+
+		'cursor',
+
+		'list-style',
+		'list-style-image',
+	);
+
 	if ( empty( $allowed_attr ) ) {
 		return $css;
 	}
@@ -2085,20 +2103,55 @@ function safecss_filter_attr( $css, $deprecated = '' ) {
 		if ( $css_item == '' ) {
 			continue;
 		}
-		$css_item = trim( $css_item );
-		$found    = false;
+
+		$css_item        = trim( $css_item );
+		$css_test_string = $css_item;
+		$found           = false;
+		$url_attr        = false;
+
 		if ( strpos( $css_item, ':' ) === false ) {
 			$found = true;
 		} else {
-			$parts = explode( ':', $css_item );
-			if ( in_array( trim( $parts[0] ), $allowed_attr ) ) {
-				$found = true;
+			$parts        = explode( ':', $css_item, 2 );
+			$css_selector = trim( $parts[0] );
+
+			if ( in_array( $css_selector, $allowed_attr, true ) ) {
+				$found    = true;
+				$url_attr = in_array( $css_selector, $css_url_data_types, true );
 			}
 		}
-		if ( $found ) {
+
+		if ( $found && $url_attr ) {
+			// Simplified: matches the sequence `url(*)`.
+			preg_match_all( '/url\([^)]+\)/', $parts[1], $url_matches );
+
+			foreach ( $url_matches[0] as $url_match ) {
+				// Clean up the URL from each of the matches above.
+				preg_match( '/^url\(\s*([\'\"]?)(.*)(\g1)\s*\)$/', $url_match, $url_pieces );
+
+				if ( empty( $url_pieces[2] ) ) {
+					$found = false;
+					break;
+				}
+
+				$url = trim( $url_pieces[2] );
+
+				if ( empty( $url ) || $url !== wp_kses_bad_protocol( $url, $allowed_protocols ) ) {
+					$found = false;
+					break;
+				} else {
+					// Remove the whole `url(*)` bit that was matched above from the CSS.
+					$css_test_string = str_replace( $url_match, '', $css_test_string );
+				}
+			}
+		}
+
+		// Remove any CSS containing containing \ ( & } = or comments, except for url() useage checked above.
+		if ( $found && ! preg_match( '%[\\\(&=}]|/\*%', $css_test_string ) ) {
 			if ( $css != '' ) {
 				$css .= ';';
 			}
+
 			$css .= $css_item;
 		}
 	}
diff --git a/tests/phpunit/tests/kses.php b/tests/phpunit/tests/kses.php
index b91fe5d386..ae1ccd342f 100644
--- a/tests/phpunit/tests/kses.php
+++ b/tests/phpunit/tests/kses.php
@@ -818,10 +818,10 @@ EOF;
 				'css'      => 'margin: 10px 20px;padding: 5px 10px',
 				'expected' => 'margin: 10px 20px;padding: 5px 10px',
 			),
-			// Parenthesis ( isn't supported.
+			// Parenthesis ( is supported for some attributes.
 			array(
 				'css'      => 'background: green url("foo.jpg") no-repeat fixed center',
-				'expected' => '',
+				'expected' => 'background: green url("foo.jpg") no-repeat fixed center',
 			),
 		);
 	}
@@ -920,4 +920,151 @@ EOF;
 			array( 'data**', false ),
 		);
 	}
+
+	/**
+	 * Test URL sanitization in the style tag.
+	 *
+	 * @dataProvider data_kses_style_attr_with_url
+	 *
+	 * @ticket 45067
+	 *
+	 * @param $input string The style attribute saved in the editor.
+	 * @param $expected string The sanitized style attribute.
+	 */
+	function test_kses_style_attr_with_url( $input, $expected ) {
+		$actual = safecss_filter_attr( $input );
+
+		$this->assertSame( $expected, $actual );
+	}
+
+	/**
+	 * Data provider testing style attribute sanitization.
+	 *
+	 * @return array Nested array of input, expected pairs.
+	 */
+	function data_kses_style_attr_with_url() {
+		return array(
+			/*
+			 * Valid use cases.
+			 */
+
+			// Double quotes.
+			array(
+				'background-image: url( "http://example.com/valid.gif" );',
+				'background-image: url( "http://example.com/valid.gif" )',
+			),
+
+			// Single quotes.
+			array(
+				"background-image: url( 'http://example.com/valid.gif' );",
+				"background-image: url( 'http://example.com/valid.gif' )",
+			),
+
+			// No quotes.
+			array(
+				'background-image: url( http://example.com/valid.gif );',
+				'background-image: url( http://example.com/valid.gif )',
+			),
+
+			// Single quotes, extra spaces.
+			array(
+				"background-image: url( '  http://example.com/valid.gif ' );",
+				"background-image: url( '  http://example.com/valid.gif ' )",
+			),
+
+			// Line breaks, single quotes.
+			array(
+				"background-image: url(\n'http://example.com/valid.gif' );",
+				"background-image: url('http://example.com/valid.gif' )",
+			),
+
+			// Tabs not spaces, single quotes.
+			array(
+				"background-image: url(\t'http://example.com/valid.gif'\t\t);",
+				"background-image: url('http://example.com/valid.gif')",
+			),
+
+			// Single quotes, absolute path.
+			array(
+				"background: url('/valid.gif');",
+				"background: url('/valid.gif')",
+			),
+
+			// Single quotes, relative path.
+			array(
+				"background: url('../wp-content/uploads/2018/10/valid.gif');",
+				"background: url('../wp-content/uploads/2018/10/valid.gif')",
+			),
+
+			// Error check: valid property not containing a URL.
+			array(
+				'background: red',
+				'background: red',
+			),
+
+			/*
+			 * Invalid use cases.
+			 */
+
+			// Attribute doesn't support URL properties.
+			array(
+				'color: url( "http://example.com/invalid.gif" );',
+				'',
+			),
+
+			// Mismatched quotes.
+			array(
+				'background-image: url( "http://example.com/valid.gif\' );',
+				'',
+			),
+
+			// Bad protocol, double quotes.
+			array(
+				'background-image: url( "bad://example.com/invalid.gif" );',
+				'',
+			),
+
+			// Bad protocol, single quotes.
+			array(
+				"background-image: url( 'bad://example.com/invalid.gif' );",
+				'',
+			),
+
+			// Bad protocol, single quotes.
+			array(
+				"background-image: url( 'bad://example.com/invalid.gif' );",
+				'',
+			),
+
+			// Bad protocol, single quotes, strange spacing.
+			array(
+				"background-image: url( '  \tbad://example.com/invalid.gif ' );",
+				'',
+			),
+
+			// Bad protocol, no quotes.
+			array(
+				'background-image: url( bad://example.com/invalid.gif );',
+				'',
+			),
+
+			// No URL inside url().
+			array(
+				'background-image: url();',
+				'',
+			),
+
+			// Malformed, no closing `)`.
+			array(
+				'background-image: url( "http://example.com" ;',
+				'',
+			),
+
+			// Malformed, no closing `"`.
+			array(
+				'background-image: url( "http://example.com );',
+				'',
+			),
+		);
+	}
 }
diff --git a/tests/phpunit/tests/shortcode.php b/tests/phpunit/tests/shortcode.php
index 790325dd26..050baa5c0a 100644
--- a/tests/phpunit/tests/shortcode.php
+++ b/tests/phpunit/tests/shortcode.php
@@ -561,8 +561,8 @@ EOF;
 				'<[gallery]>',
 			),
 			array(
-				'<div style="background:url([[gallery]])">',
-				'<div style="background:url([[gallery]])">',
+				'<div style="selector:url([[gallery]])">',
+				'<div style="selector:url([[gallery]])">',
 			),
 			array(
 				'[gallery]<div>Hello</div>[/gallery]',