Index: src/wp-admin/about.php
===================================================================
--- src/wp-admin/about.php	(revision 35530)
+++ src/wp-admin/about.php	(working copy)
@@ -134,7 +134,7 @@
 					// Image.
 					else:
 					?>
-					<img src="<?php echo esc_url( $feature['src'] ); ?>" />
+					<img src="<?php echo esc_url( $feature['src'] ); ?>" alt="" />
 					<?php endif; ?>
 				</div>
 				<h3><?php echo $feature['heading']; ?></h3>
@@ -147,7 +147,7 @@
 			<?php foreach ( $minor_features as $feature ) : ?>
 			<div class="col">
 				<div class="svg-container">
-					<img src="<?php echo esc_attr( $feature['src'] ); ?>" />
+					<img src="<?php echo esc_attr( $feature['src'] ); ?>" alt="" />
 				</div>
 				<h3><?php echo $feature['heading']; ?></h3>
 				<p><?php echo $feature['description']; ?></p>
Index: src/wp-admin/custom-header.php
===================================================================
--- src/wp-admin/custom-header.php	(revision 35530)
+++ src/wp-admin/custom-header.php	(working copy)
@@ -771,7 +771,7 @@
 	<p class="hide-if-js"><strong><?php _e( 'You need JavaScript to choose a part of the image.'); ?></strong></p>

 	<div id="crop_image" style="position: relative">
-		<img src="<?php echo esc_url( $url ); ?>" id="upload" width="<?php echo $width; ?>" height="<?php echo $height; ?>" />
+		<img src="<?php echo esc_url( $url ); ?>" id="upload" width="<?php echo $width; ?>" height="<?php echo $height; ?>" alt="" />
 	</div>

 	<input type="hidden" name="x1" id="x1" value="0"/>
Index: src/wp-admin/includes/class-wp-theme-install-list-table.php
===================================================================
--- src/wp-admin/includes/class-wp-theme-install-list-table.php	(revision 35530)
+++ src/wp-admin/includes/class-wp-theme-install-list-table.php	(working copy)
@@ -302,7 +302,7 @@

 		?>
 		<a class="screenshot install-theme-preview" href="<?php echo esc_url( $preview_url ); ?>" title="<?php echo esc_attr( $preview_title ); ?>">
-			<img src="<?php echo esc_url( $theme->screenshot_url ); ?>" width="150" />
+			<img src="<?php echo esc_url( $theme->screenshot_url ); ?>" width="150" alt="" />
 		</a>

 		<h3><?php echo $name; ?></h3>
@@ -412,7 +412,7 @@
 			<h3 class="theme-name"><?php echo $name; ?></h3>
 			<span class="theme-by"><?php printf( __( 'By %s' ), $author ); ?></span>
 			<?php if ( isset( $theme->screenshot_url ) ): ?>
-				<img class="theme-screenshot" src="<?php echo esc_url( $theme->screenshot_url ); ?>" />
+				<img class="theme-screenshot" src="<?php echo esc_url( $theme->screenshot_url ); ?>" alt="" />
 			<?php endif; ?>
 			<div class="theme-details">
 				<?php wp_star_rating( array( 'rating' => $theme->rating, 'type' => 'percent', 'number' => $theme->num_ratings ) ); ?>
Index: src/wp-admin/includes/image-edit.php
===================================================================
--- src/wp-admin/includes/image-edit.php	(revision 35530)
+++ src/wp-admin/includes/image-edit.php	(working copy)
@@ -184,7 +184,7 @@
 		<input type="hidden" id="imgedit-y-<?php echo $post_id; ?>" value="<?php echo isset( $meta['height'] ) ? $meta['height'] : 0; ?>" />

 		<div id="imgedit-crop-<?php echo $post_id; ?>" class="imgedit-crop-wrap">
-		<img id="image-preview-<?php echo $post_id; ?>" onload="imageEdit.imgLoaded('<?php echo $post_id; ?>')" src="<?php echo admin_url( 'admin-ajax.php', 'relative' ); ?>?action=imgedit-preview&amp;_ajax_nonce=<?php echo $nonce; ?>&amp;postid=<?php echo $post_id; ?>&amp;rand=<?php echo rand(1, 99999); ?>" />
+		<img id="image-preview-<?php echo $post_id; ?>" onload="imageEdit.imgLoaded('<?php echo $post_id; ?>')" src="<?php echo admin_url( 'admin-ajax.php', 'relative' ); ?>?action=imgedit-preview&amp;_ajax_nonce=<?php echo $nonce; ?>&amp;postid=<?php echo $post_id; ?>&amp;rand=<?php echo rand(1, 99999); ?>" alt="<?php esc_attr_e( 'Image preview' ); ?>" />
 		</div>

 		<div class="imgedit-submit">
Index: src/wp-admin/includes/plugin-install.php
===================================================================
--- src/wp-admin/includes/plugin-install.php	(revision 35530)
+++ src/wp-admin/includes/plugin-install.php	(working copy)
@@ -605,9 +605,9 @@
 					}
 					$contrib_username = sanitize_user( $contrib_username );
 					if ( empty( $contrib_profile ) ) {
-						echo "<li><img src='https://wordpress.org/grav-redirect.php?user={$contrib_username}&amp;s=36' width='18' height='18' />{$contrib_username}</li>";
+						echo "<li><img src='https://wordpress.org/grav-redirect.php?user={$contrib_username}&amp;s=36' width='18' height='18' alt='' />{$contrib_username}</li>";
 					} else {
-						echo "<li><a href='{$contrib_profile}' target='_blank'><img src='https://wordpress.org/grav-redirect.php?user={$contrib_username}&amp;s=36' width='18' height='18' />{$contrib_username}</a></li>";
+						echo "<li><a href='{$contrib_profile}' target='_blank'><img src='https://wordpress.org/grav-redirect.php?user={$contrib_username}&amp;s=36' width='18' height='18' alt='' />{$contrib_username}</a></li>";
 					}
 				}
 				?>
Index: src/wp-admin/includes/post.php
===================================================================
--- src/wp-admin/includes/post.php	(revision 35530)
+++ src/wp-admin/includes/post.php	(working copy)
@@ -1615,7 +1615,7 @@
 			<div class="post-locked-avatar"></div>
 			<p class="wp-tab-first" tabindex="0">
 			<span class="currently-editing"></span><br />
-			<span class="locked-saving hidden"><img src="<?php echo esc_url( admin_url( 'images/spinner-2x.gif' ) ); ?>" width="16" height="16" /> <?php _e('Saving revision&hellip;'); ?></span>
+			<span class="locked-saving hidden"><img src="<?php echo esc_url( admin_url( 'images/spinner-2x.gif' ) ); ?>" width="16" height="16" alt="" /> <?php _e( 'Saving revision&hellip;' ); ?></span>
 			<span class="locked-saved hidden"><?php _e('Your latest changes were saved as a revision.'); ?></span>
 			</p>
 			<?php
Index: src/wp-admin/js/image-edit.js
===================================================================
--- src/wp-admin/js/image-edit.js	(revision 35530)
+++ src/wp-admin/js/image-edit.js	(working copy)
@@ -165,7 +165,7 @@
 			'rand': t.intval(Math.random() * 1000000)
 		};

-		img = $('<img id="image-preview-' + postid + '" />')
+		img = $( '<img id="image-preview-' + postid + '" alt="" />' )
 			.on('load', function() {
 				var max1, max2, parent = $('#imgedit-crop-' + postid), t = imageEdit;

Index: src/wp-admin/js/inline-edit-post.js
===================================================================
--- src/wp-admin/js/inline-edit-post.js	(revision 35530)
+++ src/wp-admin/js/inline-edit-post.js	(working copy)
@@ -332,7 +332,7 @@
 				row.find('.check-column checkbox').prop('checked', false);

 				if ( lock_data.avatar_src ) {
-					avatar = $('<img class="avatar avatar-18 photo" width="18" height="18" />').attr( 'src', lock_data.avatar_src.replace(/&amp;/g, '&') );
+					avatar = $( '<img class="avatar avatar-18 photo" width="18" height="18" alt="" />' ).attr( 'src', lock_data.avatar_src.replace( /&amp;/g, '&' ) );
 					row.find('.column-title .locked-avatar').empty().append( avatar );
 				}
 				row.addClass('wp-locked');
Index: src/wp-admin/js/post.js
===================================================================
--- src/wp-admin/js/post.js	(revision 35530)
+++ src/wp-admin/js/post.js	(working copy)
@@ -131,7 +131,7 @@
 				}

 				if ( received.lock_error.avatar_src ) {
-					avatar = $('<img class="avatar avatar-64 photo" width="64" height="64" />').attr( 'src', received.lock_error.avatar_src.replace(/&amp;/g, '&') );
+					avatar = $( '<img class="avatar avatar-64 photo" width="64" height="64" alt="" />' ).attr( 'src', received.lock_error.avatar_src.replace( /&amp;/g, '&' ) );
 					wrap.find('div.post-locked-avatar').empty().append( avatar );
 				}

Index: src/wp-admin/js/press-this.js
===================================================================
--- src/wp-admin/js/press-this.js	(revision 35530)
+++ src/wp-admin/js/press-this.js	(working copy)
@@ -323,7 +323,7 @@
 					link = src;
 				}

-				newContent = '<a href="' + link + '"><img class="alignnone size-full" src="' + src + '" /></a>';
+				newContent = '<a href="' + link + '"><img class="alignnone size-full" src="' + src + '" alt="" /></a>';
 			} else {
 				newContent = '[embed]' + src + '[/embed]';
 			}
Index: src/wp-admin/update-core.php
===================================================================
--- src/wp-admin/update-core.php	(revision 35530)
+++ src/wp-admin/update-core.php	(working copy)
@@ -360,7 +360,7 @@
 		echo "
 	<tr>
 		<th scope='row' class='check-column'><input type='checkbox' name='checked[]' value='" . esc_attr( $stylesheet ) . "' /></th>
-		<td class='plugin-title'><img src='" . esc_url( $theme->get_screenshot() ) . "' width='85' height='64' style='float:left; padding: 0 5px 5px' /><strong>" . $theme->display('Name') . '</strong> ' . sprintf( __( 'You have version %1$s installed. Update to %2$s.' ), $theme->display('Version'), $theme->update['new_version'] ) . "</td>
+		<td class='plugin-title'><img src='" . esc_url( $theme->get_screenshot() ) . "' width='85' height='64' style='float:left; padding: 0 5px 5px' alt='' /><strong>" . $theme->display('Name') . '</strong> ' . sprintf( __( 'You have version %1$s installed. Update to %2$s.' ), $theme->display('Version'), $theme->update['new_version'] ) . "</td>
 	</tr>";
 	}
 ?>
Index: src/wp-includes/customize/class-wp-customize-media-control.php
===================================================================
--- src/wp-includes/customize/class-wp-customize-media-control.php	(revision 35530)
+++ src/wp-includes/customize/class-wp-customize-media-control.php	(working copy)
@@ -157,14 +157,14 @@
 					<div class="attachment-media-view attachment-media-view-{{ data.attachment.type }} {{ data.attachment.orientation }}">
 						<div class="thumbnail thumbnail-{{ data.attachment.type }}">
 							<# if ( 'image' === data.attachment.type && data.attachment.sizes && data.attachment.sizes.medium ) { #>
-								<img class="attachment-thumb" src="{{ data.attachment.sizes.medium.url }}" draggable="false" />
+								<img class="attachment-thumb" src="{{ data.attachment.sizes.medium.url }}" draggable="false" alt="" />
 							<# } else if ( 'image' === data.attachment.type && data.attachment.sizes && data.attachment.sizes.full ) { #>
-								<img class="attachment-thumb" src="{{ data.attachment.sizes.full.url }}" draggable="false" />
+								<img class="attachment-thumb" src="{{ data.attachment.sizes.full.url }}" draggable="false" alt="" />
 							<# } else if ( 'audio' === data.attachment.type ) { #>
 								<# if ( data.attachment.image && data.attachment.image.src && data.attachment.image.src !== data.attachment.icon ) { #>
-									<img src="{{ data.attachment.image.src }}" class="thumbnail" draggable="false" />
+									<img src="{{ data.attachment.image.src }}" class="thumbnail" draggable="false" alt="" />
 								<# } else { #>
-									<img src="{{ data.attachment.icon }}" class="attachment-thumb type-icon" draggable="false" />
+									<img src="{{ data.attachment.icon }}" class="attachment-thumb type-icon" draggable="false" alt="" />
 								<# } #>
 								<p class="attachment-meta attachment-meta-title">&#8220;{{ data.attachment.title }}&#8221;</p>
 								<# if ( data.attachment.album || data.attachment.meta.album ) { #>
@@ -184,7 +184,7 @@
 									</video>
 								</div>
 							<# } else { #>
-								<img class="attachment-thumb type-icon icon" src="{{ data.attachment.icon }}" draggable="false" />
+								<img class="attachment-thumb type-icon icon" src="{{ data.attachment.icon }}" draggable="false" alt="" />
 								<p class="attachment-title">{{ data.attachment.title }}</p>
 							<# } #>
 						</div>
Index: src/wp-includes/js/tinymce/plugins/wordpress/plugin.js
===================================================================
--- src/wp-includes/js/tinymce/plugins/wordpress/plugin.js	(revision 35530)
+++ src/wp-includes/js/tinymce/plugins/wordpress/plugin.js	(working copy)
@@ -100,7 +100,7 @@

 				event.content = event.content.replace( /<!--more(.*?)-->/g, function( match, moretext ) {
 					return '<img src="' + tinymce.Env.transparentSrc + '" data-wp-more="more" data-wp-more-text="' + moretext + '" ' +
-						'class="wp-more-tag mce-wp-more" title="' + title + '" data-mce-resize="false" data-mce-placeholder="1" />';
+						'class="wp-more-tag mce-wp-more" alt="" title="' + title + '" data-mce-resize="false" data-mce-placeholder="1" />';
 				});
 			}

@@ -109,7 +109,7 @@

 				event.content = event.content.replace( /<!--nextpage-->/g,
 					'<img src="' + tinymce.Env.transparentSrc + '" data-wp-more="nextpage" class="wp-more-tag mce-wp-nextpage" ' +
-						'title="' + title + '" data-mce-resize="false" data-mce-placeholder="1" />' );
+						'alt="" title="' + title + '" data-mce-resize="false" data-mce-placeholder="1" />' );
 			}

 			if ( event.load && event.format !== 'raw' && hasWpautop ) {
@@ -162,7 +162,7 @@
 		classname += ' mce-wp-' + tag;
 		title = tag === 'more' ? 'Read more...' : 'Next page';
 		title = __( title );
-		html = '<img src="' + tinymce.Env.transparentSrc + '" title="' + title + '" class="' + classname + '" ' +
+		html = '<img src="' + tinymce.Env.transparentSrc + '" alt="" title="' + title + '" class="' + classname + '" ' +
 			'data-wp-more="' + tag + '" data-mce-resize="false" data-mce-placeholder="1" />';

 		// Most common case
Index: src/wp-includes/js/tinymce/plugins/wpgallery/plugin.js
===================================================================
--- src/wp-includes/js/tinymce/plugins/wpgallery/plugin.js	(revision 35530)
+++ src/wp-includes/js/tinymce/plugins/wpgallery/plugin.js	(working copy)
@@ -10,7 +10,7 @@
 	function html( cls, data ) {
 		data = window.encodeURIComponent( data );
 		return '<img src="' + tinymce.Env.transparentSrc + '" class="wp-media mceItem ' + cls + '" ' +
-			'data-wp-media="' + data + '" data-mce-resize="false" data-mce-placeholder="1" />';
+			'data-wp-media="' + data + '" data-mce-resize="false" data-mce-placeholder="1" alt="" />';
 	}

 	function restoreMediaShortcodes( content ) {
Index: src/wp-includes/media-template.php
===================================================================
--- src/wp-includes/media-template.php	(revision 35530)
+++ src/wp-includes/media-template.php	(working copy)
@@ -291,11 +291,11 @@
 				<# if ( data.uploading ) { #>
 					<div class="media-progress-bar"><div></div></div>
 				<# } else if ( 'image' === data.type && data.sizes && data.sizes.large ) { #>
-					<img class="details-image" src="{{ data.sizes.large.url }}" draggable="false" />
+					<img class="details-image" src="{{ data.sizes.large.url }}" draggable="false" alt="" />
 				<# } else if ( 'image' === data.type && data.sizes && data.sizes.full ) { #>
-					<img class="details-image" src="{{ data.sizes.full.url }}" draggable="false" />
+					<img class="details-image" src="{{ data.sizes.full.url }}" draggable="false" alt="" />
 				<# } else if ( -1 === jQuery.inArray( data.type, [ 'audio', 'video' ] ) ) { #>
-					<img class="details-image icon" src="{{ data.icon }}" draggable="false" />
+					<img class="details-image icon" src="{{ data.icon }}" draggable="false" alt="" />
 				<# } #>

 				<# if ( 'audio' === data.type ) { #>
@@ -453,9 +453,9 @@
 				<# } else { #>
 					<div class="centered">
 						<# if ( data.image && data.image.src && data.image.src !== data.icon ) { #>
-							<img src="{{ data.image.src }}" class="thumbnail" draggable="false" />
+							<img src="{{ data.image.src }}" class="thumbnail" draggable="false" alt="" />
 						<# } else { #>
-							<img src="{{ data.icon }}" class="icon" draggable="false" />
+							<img src="{{ data.icon }}" class="icon" draggable="false" alt="" />
 						<# } #>
 					</div>
 					<div class="filename">
@@ -502,9 +502,9 @@
 				<# if ( data.uploading ) { #>
 					<div class="media-progress-bar"><div></div></div>
 				<# } else if ( 'image' === data.type && data.sizes ) { #>
-					<img src="{{ data.size.url }}" draggable="false" />
+					<img src="{{ data.size.url }}" draggable="false" alt="" />
 				<# } else { #>
-					<img src="{{ data.icon }}" class="icon" draggable="false" />
+					<img src="{{ data.icon }}" class="icon" draggable="false" alt="" />
 				<# } #>
 			</div>
 			<div class="details">
@@ -820,7 +820,7 @@

 	<script type="text/html" id="tmpl-embed-image-settings">
 		<div class="thumbnail">
-			<img src="{{ data.model.url }}" draggable="false" />
+			<img src="{{ data.model.url }}" draggable="false" alt="" />
 		</div>

 		<?php
@@ -877,7 +877,7 @@
 			<div class="embed-media-settings">
 				<div class="column-image">
 					<div class="image">
-						<img src="{{ data.model.url }}" draggable="false" />
+						<img src="{{ data.model.url }}" draggable="false" alt="" />

 						<# if ( data.attachment && window.imageEdit ) { #>
 							<div class="actions">
@@ -1208,9 +1208,9 @@
 					<dl class="gallery-item">
 						<dt class="gallery-icon">
 							<# if ( attachment.thumbnail ) { #>
-								<img src="{{ attachment.thumbnail.url }}" width="{{ attachment.thumbnail.width }}" height="{{ attachment.thumbnail.height }}" />
+								<img src="{{ attachment.thumbnail.url }}" width="{{ attachment.thumbnail.width }}" height="{{ attachment.thumbnail.height }}" alt="" />
 							<# } else { #>
-								<img src="{{ attachment.url }}" />
+								<img src="{{ attachment.url }}" alt="" />
 							<# } #>
 						</dt>
 						<# if ( attachment.caption ) { #>
@@ -1232,7 +1232,7 @@
 	</script>

 	<script type="text/html" id="tmpl-crop-content">
-		<img class="crop-image" src="{{ data.url }}">
+		<img class="crop-image" src="{{ data.url }}" alt="">
 		<div class="upload-errors"></div>
 	</script>

@@ -1240,7 +1240,7 @@
 		<h2><?php _e( 'Preview' ); ?></h2>
 		<strong><?php _e( 'As a browser icon' ); ?></strong>
 		<div class="favicon-preview">
-			<img src="images/browser.png" class="browser-preview" width="182" height="" alt=""/>
+			<img src="images/browser.png" class="browser-preview" width="182" height="" alt="" />

 			<div class="favicon">
 				<img id="preview-favicon" src="{{ data.url }}" alt="<?php esc_attr_e( 'Preview as a browser icon' ); ?>"/>
Index: src/wp-includes/media.php
===================================================================
--- src/wp-includes/media.php	(revision 35530)
+++ src/wp-includes/media.php	(working copy)
@@ -1671,7 +1671,7 @@
 ?>
 <script type="text/html" id="tmpl-wp-playlist-current-item">
 	<# if ( data.image ) { #>
-	<img src="{{ data.thumb.src }}"/>
+	<img src="{{ data.thumb.src }}" alt="" />
 	<# } #>
 	<div class="wp-playlist-caption">
 		<span class="wp-playlist-item-meta wp-playlist-item-title"><?php