CVE-2025-21621 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in org.geoserver.web:gs-web-app. A fix is available for org.geoserver.web:gs-web-app — see the affected versions and patch details below.
GeoServer Reflected Cross-Site Scripting (XSS) vulnerability in WMS GetFeatureInfo HTML format
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-21621.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2025-21621 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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
Summary
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.
Details
The WMS service setting that controls HTML auto-escaping is either disabled by default, or completely missing, in the affected versions (see workarounds).
Impact
If an attacker can control a script that is executed in the victim's browser, then they can typically fully compromise that user. Amongst other things, the attacker can:
- Perform any action within the application that the user can perform.
- View any information that the user is able to view.
- Modify any information that the user is able to modify.
- Initiate interactions with other application users, including malicious attacks, that will appear to originate from the initial victim user.
Workarounds
Changing any of the following WMS service settings should mitigate this vulnerability in most environments:
- Enable GetFeatureInfo HTML auto-escaping (available in GeoServer 2.21.3+ and 2.22.1+)
- Disable dynamic styling
- Disable GetFeatureInfo text/html MIME type
References
https://osgeo-org.atlassian.net/browse/GEOS-11297 https://github.com/geoserver/geoserver/pull/7406
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.geoserver.web:gs-web-app | all versions | 2.25.0org.geoserver.web:gs-web-app:2.25.0 |
| ☕Maven | org.geoserver:gs-wms | all versions | 2.25.0org.geoserver:gs-wms: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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-21621 can be triaged on real exposure rather than presence alone.
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 Security finds CVE-2025-21621 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.