GeoServer is an open source server that allows users to share and edit geospatial data. It is possible to bypass the default REST API security and access the index page. The REST API security handles rest and its subpaths but not rest with an extension (e.g., rest.html). The REST API index can disclose whether certain extensions are installed. This vulnerability is fixed in 2.26.3 and 2.25.6. As a workaround, in ${GEOSERVER_DATA_DIR}/security/config.xml, change the paths for the rest filter to /rest.*,/rest/** and change the paths for the gwc filter to /gwc/rest.*,/gwc/rest/** and restart GeoServer.
Use CWE-862, Osgeo vendor hub and Geoserver product page to widen CVE-2025-27505 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2025-30220, CVE-2023-25157 and CVE-2024-34711 for nearby disclosures in the same product family.