GHSA-x4r9-gmw3-hxww GeoServer has a Server-Side Request Forgery (SSRF) Vulnerability in its XML Entity Resolution

• Maven org.geoserver.web:gs-web-app: < 2.26.4 → fixed in 2.26.4 • Maven org.geoserver:gs-main: < 2.26.4 → fixed in 2.26.4 • Maven org.geoserver:gs-main: >= 2.27.0, < 2.27.3 → fixed in 2.27.3 • Maven org.geoserver.web:gs-web-app: >= 2.27.0, < 2.27.3 → fixed in 2.27.3

Summary A GeoServer that uses `ENTITY_RESOLUTION_ALLOWLIST` may allow attacker to perform unauthenticated Server-Side Request Forgery (SSRF). Details This vulnerability requires that GeoServer is set up to use a proxy base URL and the `ENTITY_RESOLUTION_ALLOWLIST` (default since 2.25.0): Impact This vulnerability allows an attacker to cause GeoServer to make requests to an unintended location. Workaround GeoServer installations are only affected by this vulnerability if they use a proxy base URL that does not contain a URL path or end with a slash (e.g., `https://somesite.org` instead of `https://somesite.org/` or `https://somesite.org/geoserver`). If the proxy base URL does not contain a path, adding a slash to the end of the URL will mitigate this vulnerability. Resources https://osgeo-org.atlassian.net/browse/GEOS-11867 https://github.com/geoserver/geoserver/pull/8622 Credits: • Le Mau Anh Phong at Verichains Cyber Force