CVE-2026-0871 is a medium-severity (CVSS 4.9) CWE-266 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.
Org.keycloak/keycloak-services: keycloak: unauthorized modification of unmanaged user attributes by administrators
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-2026-0871.
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.keycloak:keycloak-server-spi-privateReal-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. An administrator with manage-users permission can bypass the "Only administrators can view" setting for unmanaged attributes, allowing them to modify these attributes. This improper access control can lead to unauthorized changes to user profiles, even when the system is configured to restrict such modifications.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.keycloak:keycloak-server-spi-private | all versions | 26.5.2org.keycloak:keycloak-server-spi-private:26.5.2 |
Affected Products
build of keycloakredhatkeycloakredhatDetection & 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 26.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-0871 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
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.
This vulnerability is rated Moderate for Red Hat. An administrator with `manage-users` permission can modify unmanaged user attributes in Keycloak, even when the "Only administrators can view" setting is enabled. This bypass requires the realm to be configured with unmanaged attributes set to "Only administrators can…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for CVE-2026-0871 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat build of Keycloak 26.4 | rhbk/keycloak-operator-bundle:26.4.9-1 | RHSA-2026:2366 |
| Red Hat build of Keycloak 26.4.9 | rhbk/keycloak-rhel9 | RHSA-2026:2365 |
Frequently Asked Questions
Is CVE-2026-0871 in your dependencies?
Find it across Maven, including transitive dependencies.