CVE-2020-10776 is a medium-severity (CVSS 4.8) Cross-site Scripting (XSS) vulnerability in org.keycloak:keycloak-server-spi-private. A fix is available for org.keycloak:keycloak-server-spi-private — see the affected versions and patch details below.
Cross-site Scripting in keycloak
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-2020-10776 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.keycloak:keycloak-server-spi-private☕org.keycloak:keycloak-servicesReal-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
A flaw was found in Keycloak before version 12.0.0, where it is possible to add unsafe schemes for the redirect_uri parameter. This flaw allows an attacker to perform a Cross-site scripting attack.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.keycloak:keycloak-server-spi-private | all versions | 12.0.0org.keycloak:keycloak-server-spi-private:12.0.0 |
| ☕Maven | org.keycloak:keycloak-services | all versions | 12.0.0org.keycloak:keycloak-services:12.0.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.keycloak:keycloak-server-spi-private, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.keycloak:keycloak-server-spi-private to 12.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-10776 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-2020-10776 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2020-10776. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Single Sign-On 7.4.3 | see advisory | RHSA-2020:4931 |
| Red Hat Single Sign-On 7.4 for RHEL 6 | rh-sso7-keycloak-0:9.0.9-1.redhat_00001.1.el6sso | RHSA-2020:4929 |
| Red Hat Single Sign-On 7.4 for RHEL 7 | rh-sso7-keycloak-0:9.0.9-1.redhat_00001.1.el7sso | RHSA-2020:4930 |
| Red Hat Single Sign-On 7.4 for RHEL 8 | rh-sso7-keycloak-0:9.0.9-1.redhat_00001.1.el8sso | RHSA-2020:4932 |
Frequently Asked Questions
Is CVE-2020-10776 in your dependencies?
O3 Security finds CVE-2020-10776 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.