Grouped backports to the 4.8 branch.

- Posts, Post types: Apply KSES to post-by-email content,
- General: Validate host on "Are you sure?" screen,
- Posts, Post types: Remove emails from post-by-email logs,
- Media: Refactor search by filename within the admin,
- Pings/trackbacks: Apply KSES to all trackbacks,
- Comments: Apply kses when editing comments,
- Customize: Escape blogname option in underscores templates,
- REST API: Lockdown post parameter of the terms endpoint,
- Mail: Reset PHPMailer properties between use,
- Query: Validate relation in `WP_Date_Query`,
- Widgets: Escape RSS error messages for display.

Merges [54521], [54522], [54523], [54524], [54525], [54526], [54527], [54528], [54529], [54530], [54541] to the 4.8 branch.
Props voldemortensen, johnbillion, paulkevan, peterwilsoncc, xknown, dd32, audrasjb, martinkrcho, vortfu, davidbaumwald, tykoted, timothyblynjacobs, johnjamesjacoby, ehtis, matveb, talldanwp.


git-svn-id: https://develop.svn.wordpress.org/branches/4.8@54568 602fd350-edb4-49c9-b593-d223f7449a82

19 files changed, 299 insertions, 68 deletions

diff --git a/src/wp-admin/includes/ajax-actions.php b/src/wp-admin/includes/ajax-actions.php
index 8d57c00367..5347073c2f 100644
--- a/src/wp-admin/includes/ajax-actions.php
+++ b/src/wp-admin/includes/ajax-actions.php
@@ -2466,7 +2466,7 @@ function wp_ajax_query_attachments() {
 
 	// Filter query clauses to include filenames.
 	if ( isset( $query['s'] ) ) {
-		add_filter( 'posts_clauses', '_filter_query_attachment_filenames' );
+		add_filter( 'wp_allow_query_attachment_by_filename', '__return_true' );
 	}
 
 	/**
diff --git a/src/wp-admin/includes/post.php b/src/wp-admin/includes/post.php
index 52148be5d6..a2e3533645 100644
--- a/src/wp-admin/includes/post.php
+++ b/src/wp-admin/includes/post.php
@@ -1169,7 +1169,7 @@ function wp_edit_attachments_query_vars( $q = false ) {
 
 	// Filter query clauses to include filenames.
 	if ( isset( $q['s'] ) ) {
-		add_filter( 'posts_clauses', '_filter_query_attachment_filenames' );
+		add_filter( 'wp_allow_query_attachment_by_filename', '__return_true' );
 	}
 
 	return $q;
diff --git a/src/wp-includes/class-wp-query.php b/src/wp-includes/class-wp-query.php
index affd3caaec..0b44608a56 100644
--- a/src/wp-includes/class-wp-query.php
+++ b/src/wp-includes/class-wp-query.php
@@ -487,6 +487,13 @@ class WP_Query {
 	private $compat_methods = array( 'init_query_flags', 'parse_tax_query' );
 
 	/**
+	 * Controls whether an attachment query should include filenames or not.
+	 *
+	 * @since 6.0.3
+	 * @var bool
+	 */
+	protected $allow_query_attachment_by_filename = false;
+	/**
 	 * Resets query flags to false.
 	 *
 	 * The query flags are what page info WordPress was able to figure out.
@@ -1346,7 +1353,12 @@ class WP_Query {
 			}
 
 			$like = $n . $wpdb->esc_like( $term ) . $n;
-			$search .= $wpdb->prepare( "{$searchand}(({$wpdb->posts}.post_title $like_op %s) $andor_op ({$wpdb->posts}.post_excerpt $like_op %s) $andor_op ({$wpdb->posts}.post_content $like_op %s))", $like, $like, $like );
+
+			if ( ! empty( $this->allow_query_attachment_by_filename ) ) {
+				$search .= $wpdb->prepare( "{$searchand}(({$wpdb->posts}.post_title $like_op %s) $andor_op ({$wpdb->posts}.post_excerpt $like_op %s) $andor_op ({$wpdb->posts}.post_content $like_op %s) $andor_op (sq1.meta_value $like_op %s))", $like, $like, $like, $like );
+			} else {
+				$search .= $wpdb->prepare( "{$searchand}(({$wpdb->posts}.post_title $like_op %s) $andor_op ({$wpdb->posts}.post_excerpt $like_op %s) $andor_op ({$wpdb->posts}.post_content $like_op %s))", $like, $like, $like );
+			}
 			$searchand = ' AND ';
 		}
 
@@ -1683,6 +1695,16 @@ class WP_Query {
 		// Fill again in case pre_get_posts unset some vars.
 		$q = $this->fill_query_vars($q);
 
+		/**
+		 * Filters whether an attachment query should include filenames or not.
+		 *
+		 * @since 6.0.3
+		 *
+		 * @param bool $allow_query_attachment_by_filename Whether or not to include filenames.
+		 */
+		$this->allow_query_attachment_by_filename = apply_filters( 'wp_allow_query_attachment_by_filename', false );
+		remove_all_filters( 'wp_allow_query_attachment_by_filename' );
+
 		// Parse meta query
 		$this->meta_query = new WP_Meta_Query();
 		$this->meta_query->parse_query_vars( $q );
@@ -2087,7 +2109,7 @@ class WP_Query {
 			}
 		}
 
-		if ( !empty( $this->tax_query->queries ) || !empty( $this->meta_query->queries ) ) {
+		if ( ! empty( $this->tax_query->queries ) || ! empty( $this->meta_query->queries ) || ! empty( $this->allow_query_attachment_by_filename ) ) {
 			$groupby = "{$wpdb->posts}.ID";
 		}
 
@@ -2136,6 +2158,10 @@ class WP_Query {
 		}
 		$where .= $search . $whichauthor . $whichmimetype;
 
+		if ( ! empty( $this->allow_query_attachment_by_filename ) ) {
+			$join .= " LEFT JOIN {$wpdb->postmeta} AS sq1 ON ( {$wpdb->posts}.ID = sq1.post_id AND sq1.meta_key = '_wp_attached_file' )";
+		}
+
 		if ( ! empty( $this->meta_query->queries ) ) {
 			$clauses = $this->meta_query->get_sql( 'post', $wpdb->posts, 'ID', $this );
 			$join   .= $clauses['join'];
diff --git a/src/wp-includes/comment.php b/src/wp-includes/comment.php
index 6a125fca12..7d00719c96 100644
--- a/src/wp-includes/comment.php
+++ b/src/wp-includes/comment.php
@@ -2146,6 +2146,15 @@ function wp_update_comment($commentarr) {
 		return 0;
 	}
 
+	$filter_comment = false;
+	if ( ! has_filter( 'pre_comment_content', 'wp_filter_kses' ) ) {
+		$filter_comment = ! user_can( isset( $comment['user_id'] ) ? $comment['user_id'] : 0, 'unfiltered_html' );
+	}
+
+	if ( $filter_comment ) {
+		add_filter( 'pre_comment_content', 'wp_filter_kses' );
+	}
+
 	// Escape data pulled from DB.
 	$comment = wp_slash($comment);
 
@@ -2156,6 +2165,10 @@ function wp_update_comment($commentarr) {
 
 	$commentarr = wp_filter_comment( $commentarr );
 
+	if ( $filter_comment ) {
+		remove_filter( 'pre_comment_content', 'wp_filter_kses' );
+	}
+
 	// Now extract the merged array.
 	$data = wp_unslash( $commentarr );
 
diff --git a/src/wp-includes/customize/class-wp-customize-header-image-control.php b/src/wp-includes/customize/class-wp-customize-header-image-control.php
index 2fe55f4204..a65cee4d92 100644
--- a/src/wp-includes/customize/class-wp-customize-header-image-control.php
+++ b/src/wp-includes/customize/class-wp-customize-header-image-control.php
@@ -103,10 +103,10 @@ class WP_Customize_Header_Image_Control extends WP_Customize_Image_Control {
 			<# } else { #>
 
 			<button type="button" class="choice thumbnail"
-				data-customize-image-value="{{{data.header.url}}}"
+				data-customize-image-value="{{data.header.url}}"
 				data-customize-header-image-data="{{JSON.stringify(data.header)}}">
 				<span class="screen-reader-text"><?php _e( 'Set image' ); ?></span>
-				<img src="{{{data.header.thumbnail_url}}}" alt="{{{data.header.alt_text || data.header.description}}}">
+				<img src="{{data.header.thumbnail_url}}" alt="{{data.header.alt_text || data.header.description}}" />
 			</button>
 
 			<# if ( data.type === 'uploaded' ) { #>
diff --git a/src/wp-includes/customize/class-wp-customize-site-icon-control.php b/src/wp-includes/customize/class-wp-customize-site-icon-control.php
index ec662776d0..9cb1469c94 100644
--- a/src/wp-includes/customize/class-wp-customize-site-icon-control.php
+++ b/src/wp-includes/customize/class-wp-customize-site-icon-control.php
@@ -69,7 +69,7 @@ class WP_Customize_Site_Icon_Control extends WP_Customize_Cropped_Image_Control
 							<div class="favicon">
 								<img src="{{ data.attachment.sizes.full ? data.attachment.sizes.full.url : data.attachment.url }}" alt="<?php esc_attr_e( 'Preview as a browser icon' ); ?>"/>
 							</div>
-							<span class="browser-title" aria-hidden="true"><?php bloginfo( 'name' ); ?></span>
+							<span class="browser-title" aria-hidden="true"><?php echo esc_js( get_bloginfo( 'name' ) ); ?></span>
 						</div>
 						<img class="app-icon-preview" src="{{ data.attachment.sizes.full ? data.attachment.sizes.full.url : data.attachment.url }}" alt="<?php esc_attr_e( 'Preview as an app icon' ); ?>"/>
 					</div>
diff --git a/src/wp-includes/date.php b/src/wp-includes/date.php
index 96a784e58d..c6b3e65432 100644
--- a/src/wp-includes/date.php
+++ b/src/wp-includes/date.php
@@ -151,8 +151,8 @@ class WP_Date_Query {
 	 *                              'comment_date', 'comment_date_gmt'.
 	 */
 	public function __construct( $date_query, $default_column = 'post_date' ) {
-		if ( isset( $date_query['relation'] ) && 'OR' === strtoupper( $date_query['relation'] ) ) {
-			$this->relation = 'OR';
+		if ( isset( $date_query['relation'] ) ) {
+			$this->relation = $this->sanitize_relation( $date_query['relation'] );
 		} else {
 			$this->relation = 'AND';
 		}
@@ -232,6 +232,9 @@ class WP_Date_Query {
 			$this->validate_date_values( $queries );
 		}
 
+		// Sanitize the relation parameter.
+		$queries['relation'] = $this->sanitize_relation( $queries['relation'] );
+
 		foreach ( $queries as $key => $q ) {
 			if ( ! is_array( $q ) || in_array( $key, $this->time_keys, true ) ) {
 				// This is a first-order query. Trust the values and sanitize when building SQL.
@@ -1017,4 +1020,20 @@ class WP_Date_Query {
 
 		return $wpdb->prepare( "DATE_FORMAT( $column, %s ) $compare %f", $format, $time );
 	}
+
+	/**
+	 * Sanitizes a 'relation' operator.
+	 *
+	 * @since 6.0.3
+	 *
+	 * @param string $relation Raw relation key from the query argument.
+	 * @return string Sanitized relation ('AND' or 'OR').
+	 */
+	public function sanitize_relation( $relation ) {
+		if ( 'OR' === strtoupper( $relation ) ) {
+			return 'OR';
+		} else {
+			return 'AND';
+		}
+	}
 }
diff --git a/src/wp-includes/deprecated.php b/src/wp-includes/deprecated.php
index 027194a8cd..42698b92d7 100644
--- a/src/wp-includes/deprecated.php
+++ b/src/wp-includes/deprecated.php
@@ -3878,3 +3878,21 @@ function _sort_nav_menu_items( $a, $b ) {
 	else
 		return strcmp( $a->$_menu_item_sort_prop, $b->$_menu_item_sort_prop );
 }
+
+/**
+ * Filter the SQL clauses of an attachment query to include filenames.
+ *
+ * @since 4.7.0
+ * @deprecated 6.0.3
+ * @access private
+ *
+ * @param array $clauses An array including WHERE, GROUP BY, JOIN, ORDER BY,
+ *                       DISTINCT, fields (SELECT), and LIMITS clauses.
+ * @return array The unmodified clauses.
+ */
+function _filter_query_attachment_filenames( $clauses ) {
+	_deprecated_function( __FUNCTION__, '6.0.3', 'add_filter( "wp_allow_query_attachment_by_filename", "__return_true" )');
+	remove_filter( 'posts_clauses', __FUNCTION__ );
+	return $clauses;
+}
+
diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index 2dda110f01..154cd2829c 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -2369,7 +2369,7 @@ function wp_check_filetype_and_ext( $file, $filename, $mimes = null ) {
 		} else {
 			if ( $type !== $real_mime ) {
 				/*
-				 * Everything else including image/* and application/*: 
+				 * Everything else including image/* and application/*:
 				 * If the real content type doesn't match the file extension, assume it's dangerous.
 				 */
 				$type = $ext = false;
@@ -2378,7 +2378,7 @@ function wp_check_filetype_and_ext( $file, $filename, $mimes = null ) {
 		}
 	}
 
-	// The mime type must be allowed 
+	// The mime type must be allowed
 	if ( $type ) {
 		$allowed = get_allowed_mime_types();
 
@@ -2650,9 +2650,12 @@ function wp_nonce_ays( $action ) {
 	} else {
 		$html = __( 'Are you sure you want to do this?' );
 		if ( wp_get_referer() ) {
-			$html .= '</p><p>';
-			$html .= sprintf( '<a href="%s">%s</a>',
-				esc_url( remove_query_arg( 'updated', wp_get_referer() ) ),
+			$wp_http_referer = remove_query_arg( 'updated', wp_get_referer() );
+			$wp_http_referer = wp_validate_redirect( esc_url_raw( $wp_http_referer ) );
+			$html           .= '</p><p>';
+			$html           .= sprintf(
+				'<a href="%s">%s</a>',
+				esc_url( $wp_http_referer ),
 				__( 'Please try again.' )
 			);
 		}
diff --git a/src/wp-includes/media-template.php b/src/wp-includes/media-template.php
index efab0d50ea..beaddc01e5 100644
--- a/src/wp-includes/media-template.php
+++ b/src/wp-includes/media-template.php
@@ -1252,7 +1252,7 @@ function wp_print_media_templates() {
 			<div class="favicon">
 				<img id="preview-favicon" src="{{ data.url }}" alt="<?php esc_attr_e( 'Preview as a browser icon' ); ?>"/>
 			</div>
-			<span class="browser-title" aria-hidden="true"><?php bloginfo( 'name' ); ?></span>
+			<span class="browser-title" aria-hidden="true"><?php echo esc_js( get_bloginfo( 'name' ) ); ?></span>
 		</div>
 
 		<strong aria-hidden="true"><?php _e( 'As an app icon' ); ?></strong>
diff --git a/src/wp-includes/pluggable.php b/src/wp-includes/pluggable.php
index 546378111a..fbfd5c9d13 100644
--- a/src/wp-includes/pluggable.php
+++ b/src/wp-includes/pluggable.php
@@ -312,6 +312,8 @@ function wp_mail( $to, $subject, $message, $headers = '', $attachments = array()
 	$phpmailer->clearAttachments();
 	$phpmailer->clearCustomHeaders();
 	$phpmailer->clearReplyTos();
+	$phpmailer->Body    = '';
+	$phpmailer->AltBody = '';
 
 	// From email and name
 	// If we don't have a name from the input headers
diff --git a/src/wp-includes/post.php b/src/wp-includes/post.php
index 59e7ec9295..0363f9d0ee 100644
--- a/src/wp-includes/post.php
+++ b/src/wp-includes/post.php
@@ -1631,7 +1631,99 @@ function is_post_type_viewable( $post_type ) {
 		}
 	}
 
-	return $post_type->publicly_queryable || ( $post_type->_builtin && $post_type->public );
+	if ( ! is_object( $post_type ) ) {
+		return false;
+	}
+
+	$is_viewable = $post_type->publicly_queryable || ( $post_type->_builtin && $post_type->public );
+
+	/**
+	 * Filters whether a post type is considered "viewable".
+	 *
+	 * The returned filtered value must be a boolean type to ensure
+	 * `is_post_type_viewable()` only returns a boolean. This strictness
+	 * is by design to maintain backwards-compatibility and guard against
+	 * potential type errors in PHP 8.1+. Non-boolean values (even falsey
+	 * and truthy values) will result in the function returning false.
+	 *
+	 * @since 5.9.0
+	 *
+	 * @param bool         $is_viewable Whether the post type is "viewable" (strict type).
+	 * @param WP_Post_Type $post_type   Post type object.
+	 */
+	return true === apply_filters( 'is_post_type_viewable', $is_viewable, $post_type );
+}
+
+/**
+ * Determines whether a post status is considered "viewable".
+ *
+ * For built-in post statuses such as publish and private, the 'public' value will be evaluated.
+ * For all others, the 'publicly_queryable' value will be used.
+ *
+ * @since 5.7.0
+ * @since 5.9.0 Added `is_post_status_viewable` hook to filter the result.
+ *
+ * @param string|stdClass $post_status Post status name or object.
+ * @return bool Whether the post status should be considered viewable.
+ */
+function is_post_status_viewable( $post_status ) {
+	if ( is_scalar( $post_status ) ) {
+		$post_status = get_post_status_object( $post_status );
+
+		if ( ! $post_status ) {
+			return false;
+		}
+	}
+
+	if (
+		! is_object( $post_status ) ||
+		$post_status->internal ||
+		$post_status->protected
+	) {
+		return false;
+	}
+
+	$is_viewable = $post_status->publicly_queryable || ( $post_status->_builtin && $post_status->public );
+
+	/**
+	 * Filters whether a post status is considered "viewable".
+	 *
+	 * The returned filtered value must be a boolean type to ensure
+	 * `is_post_status_viewable()` only returns a boolean. This strictness
+	 * is by design to maintain backwards-compatibility and guard against
+	 * potential type errors in PHP 8.1+. Non-boolean values (even falsey
+	 * and truthy values) will result in the function returning false.
+	 *
+	 * @since 5.9.0
+	 *
+	 * @param bool     $is_viewable Whether the post status is "viewable" (strict type).
+	 * @param stdClass $post_status Post status object.
+	 */
+	return true === apply_filters( 'is_post_status_viewable', $is_viewable, $post_status );
+}
+
+/**
+ * Determines whether a post is publicly viewable.
+ *
+ * Posts are considered publicly viewable if both the post status and post type
+ * are viewable.
+ *
+ * @since 5.7.0
+ *
+ * @param int|WP_Post|null $post Optional. Post ID or post object. Defaults to global $post.
+ * @return bool Whether the post is publicly viewable.
+ */
+function is_post_publicly_viewable( $post = null ) {
+	$post = get_post( $post );
+
+	if ( ! $post ) {
+		return false;
+	}
+
+	$post_type   = get_post_type( $post );
+	$post_status = get_post_status( $post );
+
+	return is_post_type_viewable( $post_type ) && is_post_status_viewable( $post_status );
 }
 
 /**
@@ -6241,32 +6333,3 @@ function wp_add_trashed_suffix_to_post_name_for_post( $post ) {
 	clean_post_cache( $post->ID );
 	return $post_name;
 }
-
-/**
- * Filter the SQL clauses of an attachment query to include filenames.
- *
- * @since 4.7.0
- * @access private
- *
- * @global wpdb $wpdb WordPress database abstraction object.
- *
- * @param array $clauses An array including WHERE, GROUP BY, JOIN, ORDER BY,
- *                       DISTINCT, fields (SELECT), and LIMITS clauses.
- * @return array The modified clauses.
- */
-function _filter_query_attachment_filenames( $clauses ) {
-	global $wpdb;
-	remove_filter( 'posts_clauses', __FUNCTION__ );
-
-	// Add a LEFT JOIN of the postmeta table so we don't trample existing JOINs.
-	$clauses['join'] .= " LEFT JOIN {$wpdb->postmeta} AS sq1 ON ( {$wpdb->posts}.ID = sq1.post_id AND sq1.meta_key = '_wp_attached_file' )";
-
-	$clauses['groupby'] = "{$wpdb->posts}.ID";
-
-	$clauses['where'] = preg_replace(
-		"/\({$wpdb->posts}.post_content (NOT LIKE|LIKE) (\'[^']+\')\)/",
-		"$0 OR ( sq1.meta_value $1 $2 )",
-		$clauses['where'] );
-
-	return $clauses;
-}
diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php
index 43d057e167..a0f05fc9c2 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php
@@ -49,7 +49,7 @@ class WP_REST_Attachments_Controller extends WP_REST_Posts_Controller {
 
 		// Filter query clauses to include filenames.
 		if ( isset( $query_args['s'] ) ) {
-			add_filter( 'posts_clauses', '_filter_query_attachment_filenames' );
+			add_filter( 'wp_allow_query_attachment_by_filename', '__return_true' );
 		}
 
 		return $query_args;
diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-terms-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-terms-controller.php
index 299b034329..1cad17acca 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-terms-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-terms-controller.php
@@ -133,6 +133,35 @@ class WP_REST_Terms_Controller extends WP_REST_Controller {
 	}
 
 	/**
+	 * Checks if the terms for a post can be read.
+	 *
+	 * @since 6.0.3
+	 *
+	 * @param WP_Post         $post    Post object.
+	 * @param WP_REST_Request $request Full details about the request.
+	 * @return bool Whether the terms for the post can be read.
+	 */
+	public function check_read_terms_permission_for_post( $post, $request ) {
+		// If the requested post isn't associated with this taxonomy, deny access.
+		if ( ! is_object_in_taxonomy( $post->post_type, $this->taxonomy ) ) {
+			return false;
+		}
+
+		// Grant access if the post is publicly viewable.
+		if ( is_post_publicly_viewable( $post ) ) {
+			return true;
+		}
+
+		// Otherwise grant access if the post is readable by the logged in user.
+		if ( current_user_can( 'read_post', $post->ID ) ) {
+			return true;
+		}
+
+		// Otherwise, deny access.
+		return false;
+	}
+
+	/**
 	 * Checks if a request has access to read terms in the specified taxonomy.
 	 *
 	 * @since 4.7.0
@@ -143,12 +172,43 @@ class WP_REST_Terms_Controller extends WP_REST_Controller {
 	 */
 	public function get_items_permissions_check( $request ) {
 		$tax_obj = get_taxonomy( $this->taxonomy );
+
 		if ( ! $tax_obj || ! $this->check_is_taxonomy_allowed( $this->taxonomy ) ) {
 			return false;
 		}
+
 		if ( 'edit' === $request['context'] && ! current_user_can( $tax_obj->cap->edit_terms ) ) {
-			return new WP_Error( 'rest_forbidden_context', __( 'Sorry, you are not allowed to edit terms in this taxonomy.' ), array( 'status' => rest_authorization_required_code() ) );
+			return new WP_Error(
+				'rest_forbidden_context',
+				__( 'Sorry, you are not allowed to edit terms in this taxonomy.' ),
+				array( 'status' => rest_authorization_required_code() )
+			);
+		}
+
+		if ( ! empty( $request['post'] ) ) {
+			$post = get_post( $request['post'] );
+
+			if ( ! $post ) {
+				return new WP_Error(
+					'rest_post_invalid_id',
+					__( 'Invalid post ID.' ),
+					array(
+						'status' => 400,
+					)
+				);
+			}
+
+			if ( ! $this->check_read_terms_permission_for_post( $post, $request ) ) {
+				return new WP_Error(
+					'rest_forbidden_context',
+					__( 'Sorry, you are not allowed to view terms for this post.' ),
+					array(
+						'status' => rest_authorization_required_code(),
+					)
+				);
+			}
 		}
+
 		return true;
 	}
 
diff --git a/src/wp-includes/widgets.php b/src/wp-includes/widgets.php
index fbbdcf5f55..9cf2d12f76 100644
--- a/src/wp-includes/widgets.php
+++ b/src/wp-includes/widgets.php
@@ -1233,7 +1233,7 @@ function wp_widget_rss_output( $rss, $args = array() ) {
 
 	if ( is_wp_error($rss) ) {
 		if ( is_admin() || current_user_can('manage_options') )
-			echo '<p><strong>' . __( 'RSS Error:' ) . '</strong> ' . $rss->get_error_message() . '</p>';
+			echo '<p><strong>' . __( 'RSS Error:' ) . '</strong> ' . esc_html( $rss->get_error_message() ) . '</p>';
 		return;
 	}
 
@@ -1342,7 +1342,7 @@ function wp_widget_rss_form( $args, $inputs = null ) {
 	$args['show_date']      = isset( $args['show_date'] ) ? (int) $args['show_date'] : (int) $inputs['show_date'];
 
 	if ( ! empty( $args['error'] ) ) {
-		echo '<p class="widget-error"><strong>' . __( 'RSS Error:' ) . '</strong> ' . $args['error'] . '</p>';
+		echo '<p class="widget-error"><strong>' . __( 'RSS Error:' ) . '</strong> ' . esc_html( $args['error'] ) . '</p>';
 	}
 
 	$esc_number = esc_attr( $args['number'] );
diff --git a/src/wp-mail.php b/src/wp-mail.php
index 35fb24aed2..ccbfcb1671 100644
--- a/src/wp-mail.php
+++ b/src/wp-mail.php
@@ -60,6 +60,9 @@ if( 0 === $count ) {
 	wp_die( __('There doesn&#8217;t seem to be any new mail.') );
 }
 
+// Always run as an unauthenticated user.
+wp_set_current_user( 0 );
+
 for ( $i = 1; $i <= $count; $i++ ) {
 
 	$message = $pop3->get($i);
@@ -124,8 +127,6 @@ for ( $i = 1; $i <= $count; $i++ ) {
 					$author = trim($line);
 				$author = sanitize_email($author);
 				if ( is_email($author) ) {
-					/* translators: Post author email address */
-					echo '<p>' . sprintf(__('Author is %s'), $author) . '</p>';
 					$userdata = get_user_by('email', $author);
 					if ( ! empty( $userdata ) ) {
 						$post_author = $userdata->ID;
diff --git a/src/wp-trackback.php b/src/wp-trackback.php
index 86e17b965d..7250859cc9 100644
--- a/src/wp-trackback.php
+++ b/src/wp-trackback.php
@@ -13,6 +13,9 @@ if (empty($wp)) {
 	wp( array( 'tb' => '1' ) );
 }
 
+// Always run as an unauthenticated user.
+wp_set_current_user( 0 );
+
 /**
  * Response to a trackback.
  *
diff --git a/tests/phpunit/tests/query/search.php b/tests/phpunit/tests/query/search.php
index dedfa47e26..3b5a61076a 100644
--- a/tests/phpunit/tests/query/search.php
+++ b/tests/phpunit/tests/query/search.php
@@ -370,7 +370,7 @@ class Tests_Query_Search extends WP_UnitTestCase {
 		) );
 
 		add_post_meta( $attachment, '_wp_attached_file', 'some-image1.png', true );
-		add_filter( 'posts_clauses', '_filter_query_attachment_filenames' );
+		add_filter( 'wp_allow_query_attachment_by_filename', '__return_true' );
 
 		// Pass post_type a string value.
 		$q = new WP_Query( array(
@@ -396,7 +396,7 @@ class Tests_Query_Search extends WP_UnitTestCase {
 		) );
 
 		add_post_meta( $attachment, '_wp_attached_file', 'some-image2.png', true );
-		add_filter( 'posts_clauses', '_filter_query_attachment_filenames' );
+		add_filter( 'wp_allow_query_attachment_by_filename', '__return_true' );
 
 		// Pass post_type an array value.
 		$q = new WP_Query( array(
@@ -447,7 +447,7 @@ class Tests_Query_Search extends WP_UnitTestCase {
 
 		add_post_meta( $attachment, '_wp_attached_file', 'some-image4.png', true );
 		add_post_meta( $attachment, '_test_meta_key', 'value', true );
-		add_filter( 'posts_clauses', '_filter_query_attachment_filenames' );
+		add_filter( 'wp_allow_query_attachment_by_filename', '__return_true' );
 
 		// Pass post_type a string value.
 		$q = new WP_Query( array(
@@ -483,7 +483,7 @@ class Tests_Query_Search extends WP_UnitTestCase {
 		wp_set_post_terms( $attachment, 'test', 'post_tag' );
 
 		add_post_meta( $attachment, '_wp_attached_file', 'some-image5.png', true );
-		add_filter( 'posts_clauses', '_filter_query_attachment_filenames' );
+		add_filter( 'wp_allow_query_attachment_by_filename', '__return_true' );
 
 		// Pass post_type a string value.
 		$q = new WP_Query( array(
@@ -506,22 +506,37 @@ class Tests_Query_Search extends WP_UnitTestCase {
 	/**
 	 * @ticket 22744
 	 */
-	public function test_filter_query_attachment_filenames_unhooks_itself() {
-		add_filter( 'posts_clauses', '_filter_query_attachment_filenames' );
+	public function test_wp_query_removes_filter_wp_allow_query_attachment_by_filename() {
+		$attachment = self::factory()->post->create(
+			array(
+				'post_type'    => 'attachment',
+				'post_status'  => 'publish',
+				'post_title'   => 'bar foo',
+				'post_content' => 'foo bar',
+				'post_excerpt' => 'This post has foo',
+			)
+		);
 
-		apply_filters( 'posts_clauses', array(
-			'where'    => '',
-			'groupby'  => '',
-			'join'     => '',
-			'orderby'  => '',
-			'distinct' => '',
-			'fields'   => '',
-			'limit'    => '',
-		) );
+		add_post_meta( $attachment, '_wp_attached_file', 'some-image1.png', true );
+		add_filter( 'wp_allow_query_attachment_by_filename', '__return_true' );
 
-		$result = has_filter( 'posts_clauses', '_filter_query_attachment_filenames' );
+		$q = new WP_Query(
+			array(
+				's'           => 'image1',
+				'fields'      => 'ids',
+				'post_type'   => 'attachment',
+				'post_status' => 'inherit',
+			)
+		);
+
+		$this->assertSame( array( $attachment ), $q->posts );
 
-		$this->assertFalse( $result );
+		/*
+		 * WP_Query should have removed the wp_allow_query_attachment_by_filename filter
+		 * and thus not match the attachment created above
+		 */
+		$q->get_posts();
+		$this->assertEmpty( $q->posts );
 	}
 
 	public function filter_posts_search( $sql ) {
diff --git a/tests/phpunit/tests/rest-api/rest-comments-controller.php b/tests/phpunit/tests/rest-api/rest-comments-controller.php
index 502a6d2c5b..c7aa20bfba 100644
--- a/tests/phpunit/tests/rest-api/rest-comments-controller.php
+++ b/tests/phpunit/tests/rest-api/rest-comments-controller.php
@@ -2590,6 +2590,7 @@ class WP_Test_REST_Comments_Controller extends WP_Test_REST_Controller_Testcase
 				'content'           => '<div>div</div> <strong>strong</strong> <script>oh noes</script>',
 				'author_name'       => '<div>div</div> <strong>strong</strong> <script>oh noes</script>',
 				'author_user_agent' => '<div>div</div> <strong>strong</strong> <script>oh noes</script>',
+				'author'            => self::$editor_id,
 			), array(
 				'content' => array(
 					'raw'      => 'div <strong>strong</strong> oh noes',
@@ -2597,6 +2598,7 @@ class WP_Test_REST_Comments_Controller extends WP_Test_REST_Controller_Testcase
 				),
 				'author_name'       => 'div strong',
 				'author_user_agent' => 'div strong',
+				'author'            => self::$editor_id,
 			) );
 		} else {
 			$this->assertTrue( current_user_can( 'unfiltered_html' ) );
@@ -2604,6 +2606,7 @@ class WP_Test_REST_Comments_Controller extends WP_Test_REST_Controller_Testcase
 				'content'           => '<div>div</div> <strong>strong</strong> <script>oh noes</script>',
 				'author_name'       => '<div>div</div> <strong>strong</strong> <script>oh noes</script>',
 				'author_user_agent' => '<div>div</div> <strong>strong</strong> <script>oh noes</script>',
+				'author'            => self::$editor_id,
 			), array(
 				'content' => array(
 					'raw'      => '<div>div</div> <strong>strong</strong> <script>oh noes</script>',
@@ -2611,6 +2614,7 @@ class WP_Test_REST_Comments_Controller extends WP_Test_REST_Controller_Testcase
 				),
 				'author_name'       => 'div strong',
 				'author_user_agent' => 'div strong',
+				'author'            => self::$editor_id,
 			) );
 		}
 	}
@@ -2622,6 +2626,7 @@ class WP_Test_REST_Comments_Controller extends WP_Test_REST_Controller_Testcase
 			'content'           => '\\\&\\\ &amp; &invalid; < &lt; &amp;lt;',
 			'author_name'       => '\\\&\\\ &amp; &invalid; < &lt; &amp;lt;',
 			'author_user_agent' => '\\\&\\\ &amp; &invalid; < &lt; &amp;lt;',
+			'author'            => self::$superadmin_id,
 		), array(
 			'content' => array(
 				'raw'      => '\\\&\\\ &amp; &invalid; < &lt; &amp;lt;',
@@ -2629,6 +2634,7 @@ class WP_Test_REST_Comments_Controller extends WP_Test_REST_Controller_Testcase
 			),
 			'author_name'       => '\\\&amp;\\\ &amp; &amp;invalid; &lt; &lt; &amp;lt;',
 			'author_user_agent' => '\\\&\\\ &amp; &invalid; &lt; &lt; &amp;lt;',
+			'author'            => self::$superadmin_id,
 		) );
 	}
 
@@ -2639,6 +2645,7 @@ class WP_Test_REST_Comments_Controller extends WP_Test_REST_Controller_Testcase
 			'content'           => '<div>div</div> <strong>strong</strong> <script>oh noes</script>',
 			'author_name'       => '<div>div</div> <strong>strong</strong> <script>oh noes</script>',
 			'author_user_agent' => '<div>div</div> <strong>strong</strong> <script>oh noes</script>',
+			'author'            => self::$superadmin_id,
 		), array(
 			'content' => array(
 				'raw'      => '<div>div</div> <strong>strong</strong> <script>oh noes</script>',
@@ -2646,6 +2653,7 @@ class WP_Test_REST_Comments_Controller extends WP_Test_REST_Controller_Testcase
 			),
 			'author_name'       => 'div strong',
 			'author_user_agent' => 'div strong',
+			'author'            => self::$superadmin_id,
 		) );
 	}