CVE-2021-25931 is a high-severity (CVSS 8.8) Cross-Site Request Forgery (CSRF) vulnerability in org.opennms:opennms. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for org.opennms:opennms — see the affected versions and patch details below.
Cross-Site Request Forgery in OpenNMS Horizon
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2021-25931.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
org.opennms:opennmsReal-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
In OpenNMS Horizon, versions opennms-1-0-stable through opennms-27.1.0-1; OpenNMS Meridian, versions meridian-foundation-2015.1.0-1 through meridian-foundation-2019.1.18-1; meridian-foundation-2020.1.0-1 through meridian-foundation-2020.1.6-1 are vulnerable to CSRF, due to no CSRF protection at /opennms/admin/userGroupView/users/updateUser. This flaw allows assigning ROLE_ADMIN security role to a normal user. Using this flaw, an attacker can trick the admin user to assign administrator privileges to a normal user by enticing him to click upon an attacker-controlled website.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.opennms:opennms | ≥ 1.0.0&&< 27.1.1 | 27.1.1org.opennms:opennms:27.1.1 |
Affected Products
horizonopennmsmeridianopennmsResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.opennms:opennms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.opennms:opennms to 27.1.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-25931 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.
Frequently Asked Questions
Is CVE-2021-25931 in your dependencies?
Find it across Maven, including transitive dependencies.