CVE-2025-21621 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in org.geoserver.web:gs-web-app. O3 Security confirms whether CVE-2025-21621 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
GeoServer Reflected Cross-Site Scripting (XSS) vulnerability in WMS GetFeatureInfo HTML format
Real-World Exposure
org.geoserver.web:gs-web-app☕org.geoserver:gs-wmsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
GeoServer is an open source server that allows users to share and edit geospatial data. Prior to version 2.25.0, a reflected cross-site scripting (XSS) vulnerability exists in the WMS GetFeatureInfo HTML output format that enables a remote attacker to execute arbitrary JavaScript code in a victim's browser through specially crafted SLD_BODY parameters. This issue has been patched in version 2.25.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.geoserver.web:gs-web-app | all versions | 2.25.0 |
| ☕Maven | org.geoserver:gs-wms | all versions | 2.25.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.geoserver.web:gs-web-app. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.geoserver.web:gs-web-app to 2.25.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-21621 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2025-21621 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2025-21621. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-21621 in your dependencies?
O3 detects CVE-2025-21621 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.