A flaw was found in Keycloak. This improper input validation vulnerability occurs because Keycloak accepts RFC-compliant matrix parameters in URL path segments, while common reverse proxy configurations may ignore or mishandle them. A remote attacker can craft requests to mask path segments, potentially bypassing proxy-level path filtering. This could expose administrative or sensitive endpoints that operators believe are not externally reachable.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-v897-pv23-r8cw Keycloak has an improper input validation vulnerability
Fixes

Solution

No solution given by the vendor.


Workaround

To mitigate this issue, ensure that all administrative and sensitive endpoints within Keycloak are adequately protected by robust authentication and authorization policies, independent of any reverse proxy path filtering. Operators should review Keycloak's internal access controls to confirm that access to these endpoints is restricted to authorized users and roles.

History

Fri, 16 Jan 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Low


Thu, 15 Jan 2026 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 15 Jan 2026 12:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in Keycloak. This improper input validation vulnerability occurs because Keycloak accepts RFC-compliant matrix parameters in URL path segments, while common reverse proxy configurations may ignore or mishandle them. A remote attacker can craft requests to mask path segments, potentially bypassing proxy-level path filtering. This could expose administrative or sensitive endpoints that operators believe are not externally reachable.
Title Org.keycloak/keycloak-quarkus-server: keycloak: proxy bypass due to improper handling of matrix parameters in url paths
First Time appeared Redhat
Redhat build Keycloak
Redhat jboss Enterprise Application Platform
Redhat jbosseapxp
Weaknesses CWE-20
CPEs cpe:/a:redhat:build_keycloak:
cpe:/a:redhat:jboss_enterprise_application_platform:8
cpe:/a:redhat:jbosseapxp
Vendors & Products Redhat
Redhat build Keycloak
Redhat jboss Enterprise Application Platform
Redhat jbosseapxp
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-01-15T14:45:41.540Z

Reserved: 2026-01-15T06:43:41.332Z

Link: CVE-2026-0976

cve-icon Vulnrichment

Updated: 2026-01-15T14:45:37.752Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-01-15T13:16:04.910

Modified: 2026-01-16T15:55:33.063

Link: CVE-2026-0976

cve-icon Redhat

Severity : Low

Publid Date: 2026-01-15T00:00:00Z

Links: CVE-2026-0976 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses