Vulnerabilidad en diversos parámetros en YITH Maintenance Mode de WordPress (CVE-2021-36845)

Múltiples vulnerabilidades de tipo Cross-Site Scripting (XSS) Almacenado y Autenticado en YITH Maintenance Mode (plugin de WordPress) versiones anteriores a 1.3.8 incluyéndola, hay 46 parámetros vulnerables que fueron pasados por alto por el proveedor mientras parcheaba la versión 1.3.7 a la 1.3.8. Parámetros vulnerables: 1 - Pestaña "Newsletter", parámetro &yith_maintenance_newsletter_submit_label: el payload debe comenzar con un símbolo de comillas simples (') para romper el contexto, es decir: NOTIFY ME' autofocus onfocus=alert(/Visse/);// v=' - este payload se autodesencadenará mientras el administrador visite esta página/pestaña. 2 - Problemas de la pestaña "General", parámetros vulnerables: &yith_maintenance_message, &yith_maintenance_custom_style, &yith_maintenance_mascotte, &yith_maintenance_title_font[size], &yith_maintenance_title_font[family], &yith_maintenance_title_font[color], &yith_maintenance_paragraph_font[size], &yith_maintenance_paragraph_font[family], &yith_maintenance_paragraph_font[color], &yith_maintenance_border_top. 3 - Problemas con la pestaña "Background", parámetros vulnerables: &yith_maintenance_background_image, &yith_maintenance_background_color. 4 - Problemas con la pestaña "Logo", parámetros vulnerables: &yith_maintenance_logo_image, &yith_maintenance_logo_tagline_font, &yith_maintenance_logo_tagline_font[size], &yith_maintenance_logo_tagline_font[family], &yith_maintenance_logo_tagline_font[color]. 5 - Problemas con la pestaña "Newsletter", parámetros vulnerables: &yith_maintenance_newsletter_email_font[size], &yith_maintenance_newsletter_email_font[family], &yith_maintenance_newsletter_email_font[color], &yith_maintenance_newsletter_submit_font[size], &yith_maintenance_newsletter_submit_font[family], &yith_maintenance_newsletter_submit_font[color], &yith_maintenance_newsletter_submit_background, &yith_maintenance_newsletter_submit_background_hover, &yith_maintenance_newsletter_title, &yith_maintenance_newsletter_action, &yith_maintenance_newsletter_email_label, &yith_maintenance_newsletter_email_name, &yith_maintenance_newsletter_submit_label, &yith_maintenance_newsletter_hidden_fields. 6 - Problemas de la pestaña "Socials", parámetros vulnerables: &yith_maintenance_socials_facebook, &yith_maintenance_socials_twitter, &yith_maintenance_socials_gplus, &yith_maintenance_socials_youtube, &yith_maintenance_socials_rss, &yith_maintenance_socials_skype, &yith_maintenance_socials_email, &yith_maintenance_socials_behance, &yith_maintenance_socials_dribble, &yith_maintenance_socials_flickr, &yith_maintenance_socials_instagram, &yith_maintenance_socials_pinterest, &yith_maintenance_socials_tumblr, &yith_maintenance_socials_linkedin