CVE-2020-5231 is a medium-severity (CVSS 6.5) CWE-285 vulnerability in org.opencastproject:opencast-kernel. 1 public exploit reference exists, so weaponization risk is real. A fix is available for org.opencastproject:opencast-kernel — see the affected versions and patch details below.
Users with ROLE_COURSE_ADMIN can create new users in Opencast
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-2020-5231 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 378,156 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.opencastproject:opencast-kernel☕org.opencastproject:opencast-kernelReal-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
Impact
Users with the role ROLE_COURSE_ADMIN can use the user-utils endpoint to create new users not including the role ROLE_ADMIN. For example:
# Use the admin to create a new user with ROLE_COURSE_ADMIN using the admin user.
# We expect this to work.
% curl -i -u admin:opencast 'https://example.opencast.org/user-utils/xy.json' -X PUT \
--data 'password=f&roles=%5B%22ROLE_COURSE_ADMIN%22%5D'
HTTP/2 201
# Use the new user to create more new users.
# We don't expüect a user with just role ROLE_COURSE_ADMIN to succeed.
# But it does work
% curl -i -u xy:f 'https://example.opencast.org/user-utils/ab.json' -X PUT \
--data 'password=f&roles=%5B%22ROLE_COURSE_ADMIN%22%5D'
HTTP/2 201
ROLE_COURSE_ADMIN is a non-standard role in Opencast which is referenced neither in the documentation nor in any code (except for tests) but only in the security configuration. From the name – implying an admin for a specific course – users would never expect that this role allows user creation.
Patches
This issue is fixed in 7.6 and 8.1 which both ship a new default security configuration.
Workarounds
You can fix this issue by removing all instances of ROLE_COURSE_ADMIN in your organization's security configuration (etc/security/mh_default_org.xml by default).
For more information
If you have any questions or comments about this advisory:
- Open an issue in opencast/opencast
- For security-relevant information, email us at [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.opencastproject:opencast-kernel | all versions | 7.6org.opencastproject:opencast-kernel:7.6 |
| ☕Maven | org.opencastproject:opencast-kernel | ≥ 8.0&&< 8.1 | 8.1org.opencastproject:opencast-kernel:8.1 |
Research 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.opencastproject:opencast-kernel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.opencastproject:opencast-kernel to 7.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-5231 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-2020-5231 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2020-5231. 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-2020-5231 in your dependencies?
O3 Security finds CVE-2020-5231 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.