MapServer is a system for developing web-based GIS applications. Prior to 8.6.4, MapServer's PostGIS runtime filter translation in src/mappostgis.cpp and msPostGISLayerTranslateFilter() treats a filteritem as numeric when CONNECTIONTYPE POSTGIS and metadata such as gml_<item>_type=Integer are configured, but it does not verify that attacker-controlled CGI qstring or OGC API Features featureId input is a numeric literal. The unquoted input is concatenated into the generated PostgreSQL/PostGIS predicate, allowing an unauthenticated remote attacker with access to an affected query endpoint to bypass predicates, enumerate unintended records, perform boolean-based or time-based SQL injection, and increase database load. The issue does not by itself establish database modification capabilities. This issue is fixed in version 8.6.4.