Microsoft’s October notice schedules default disabling of browser-native XSLT in Edge 159 for mid-December 2026. It covers XSLTProcessor and XML processing instructions referring to XSLT stylesheets, not CSS stylesheets. The temporary XSLTEnabled policy is planned for removal in Edge 176 in summer 2027. Official policy documentation also describes it as temporary, so dependencies in internal web applications and device-management interfaces need checking and migration to supported alternatives.