This plugin does have several instances of the “unescaped” functions in question, so it is currently susceptible to that vulnerability.
There seem to be three affected files. I’ll try to tackle them one at a time.
In co-authors-plus/co-authors-plus.php, you need to replace the following lines to eliminate the issue:
Line 426 should be changed to read: $author_filter_url = esc_url( add_query_arg( $args, admin_url( 'edit.php' ) ) );
Line 1132 should be changed to read: $views['mine'] = $view_mine = '<a' . $class . ' href="' . esc_url( add_query_arg( $mine_args, admin_url( 'edit.php' ) ) ) . '">' . __( 'Mine', 'co-authors-plus' ) . '</a>';
Lines 1150 to 1156 inclusive should be changed to:
var coAuthorsPlus_ajax_suggest_link = '<?php echo esc_url( add_query_arg(
array(
'action' => 'coauthors_ajax_suggest',
'post_type' => get_post_type(),
),
wp_nonce_url( 'admin-ajax.php', 'coauthors-search' )
) ); ?>';
In co-authors-plus/php/class-coauthors-guest-authors.php you need to make the following lines read as follows:
Line 199: $redirect_to = esc_url( add_query_arg( 'message', 'guest-author-created', $edit_link ) );
Line 264: $redirect_to = esc_url( add_query_arg( $args, admin_url( $this->parent_page ) ) );
Line 451: echo '<form method="POST" action="' . esc_url( add_query_arg( 'page', 'view-guest-authors', admin_url( $this->parent_page ) ) ) . '">';
Line 1282: $create_guest_author_link = esc_url( add_query_arg( $query_args, admin_url( $this->parent_page ) ) );
Line 1326: $link = esc_url( add_query_arg( 'author_name', $author_nicename, home_url() ) );
Line 1334: $link = esc_url( add_query_arg( 'author_name', $author_nicename, home_url() ) );
In co-authors-plus/php/class-coauthors-wp-list-table.php you need to make the following lines read as follows:
Line 197: $item_delete_link = esc_url( add_query_arg( $args, menu_page_url( 'view-guest-authors', false ) ) );
Line 250: return '<a href="' . esc_url( add_query_arg( 'author_name', $item->user_login, admin_url( 'edit.php' ) ) ) . '">' . $count . '</a>';
I need to make one correction to the above changes, because it requires a different method of escaping. Lines 1150 to 1156 inclusive of co-authors-plus/co-authors-plus.php should, therefore, be changed to:
var coAuthorsPlus_ajax_suggest_link = '<?php echo esc_url_raw( add_query_arg(
array(
'action' => 'coauthors_ajax_suggest',
'post_type' => get_post_type(),
),
wp_nonce_url( 'admin-ajax.php', 'coauthors-search' )
) ); ?>';
