A flaw was found in Keycloak. A low-privilege user, with knowledge of user credentials and client ID, can bypass a security control intended to disable the implicit flow in OpenID Connect (OIDC) clients. By manipulating client data during a session restart, an attacker can obtain an access token that should not be available. This vulnerability can also lead to the exposure of these access tokens in server logs, proxy logs, and HTTP Referrer headers, resulting in sensitive information disclosure.

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Advisories

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Fixes

Solution

No solution given by the vendor.


Workaround

To mitigate this issue, restrict network access to the Keycloak authentication endpoint to trusted clients and networks. Implement firewall rules to control inbound connections to the Keycloak service ports, thereby reducing the attack surface and limiting who can initiate authentication flows and potentially exploit the implicit flow bypass. If the Keycloak service is reloaded or restarted, ensure these network restrictions remain in effect.

History

Tue, 19 May 2026 12:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Tue, 19 May 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Tue, 19 May 2026 11:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in Keycloak. A low-privilege user, with knowledge of user credentials and client ID, can bypass a security control intended to disable the implicit flow in OpenID Connect (OIDC) clients. By manipulating client data during a session restart, an attacker can obtain an access token that should not be available. This vulnerability can also lead to the exposure of these access tokens in server logs, proxy logs, and HTTP Referrer headers, resulting in sensitive information disclosure.
Title Keycloak: keycloak: access token disclosure and implicit flow bypass via forged client data
First Time appeared Redhat
Redhat build Keycloak
Weaknesses CWE-472
CPEs cpe:/a:redhat:build_keycloak:
Vendors & Products Redhat
Redhat build Keycloak
References
Metrics cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-05-19T12:00:14.931Z

Reserved: 2026-04-30T22:21:27.850Z

Link: CVE-2026-7571

cve-icon Vulnrichment

Updated: 2026-05-19T11:58:48.969Z

cve-icon NVD

Status : Received

Published: 2026-05-19T12:16:19.820

Modified: 2026-05-19T12:16:19.820

Link: CVE-2026-7571

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-05-19T10:50:49Z

Links: CVE-2026-7571 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-05-19T12:30:05Z

Weaknesses