A flaw was found in the SAML HTTP-Redirect binding implementation of Keycloak. The issue occurs because the server processes percent-encoded parameter names (like %53AMLResponse) while the signature verification logic only checks literal parameter names. An attacker can use this discrepancy to provide a crafted, unsigned SAML message that the server processes instead of a legitimately signed one, leading to full account takeover of federated users.

Project Subscriptions

Vendors Products
Red Hat Subscribe
Red Hat Build Of Keycloak 26.4 Subscribe
Build Keycloak Subscribe
Build Of Keycloak Subscribe
Red Hat Single Sign On Subscribe
Single Sign-on Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

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. --- CME Mitigation Guidance (2026-11-06) --- Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure. The highest-value action is to align query parameter parsing between signature verification and request processing in Keycloak's SAML HTTP-Redirect binding so percent-encoded parameter names cannot evade signature checks: upgrade to the fixed Rhbk/Keycloak Rhel/Keycloak Services builds, which eliminates the parsing discrepancy between raw query parameter signature verification and decoded parameter processing in the SAML redirect binding, closing crafted HTTP GET request containing a percent-encoded unsigned SAML parameter placed before a legitimately signed parameter. Until patched, this is a concern on Keycloak instances configured to use SAML HTTP-Redirect binding for federated identity, so Audit and restrict account registration on external Identity Providers to prevent attackers from capturing legitimately signed redirect-binding messages. These controls limit blast radius and contain exploitation, but they do not fix the underlying SAML parameter parsing discrepancy signature bypass — apply the upstream patch to fully remediate.

History

Sat, 07 Nov 2026 15:45:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:build_keycloak:
References

Sat, 07 Nov 2026 15:00:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:build_keycloak:26.6::el9
References

Fri, 06 Nov 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Important


Thu, 05 Nov 2026 17:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 05 Nov 2026 17:15:00 +0000

Type Values Removed Values Added
First Time appeared Red Hat
Red Hat red Hat Build Of Keycloak 26.4
Redhat build Of Keycloak
Redhat single Sign-on
Vendors & Products Red Hat
Red Hat red Hat Build Of Keycloak 26.4
Redhat build Of Keycloak
Redhat single Sign-on

Thu, 05 Nov 2026 13:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in the SAML HTTP-Redirect binding implementation of Keycloak. The issue occurs because the server processes percent-encoded parameter names (like %53AMLResponse) while the signature verification logic only checks literal parameter names. An attacker can use this discrepancy to provide a crafted, unsigned SAML message that the server processes instead of a legitimately signed one, leading to full account takeover of federated users.
Title Keycloak-services: keycloak-services: saml redirect binding signature bypass via percent-encoded parameter names
First Time appeared Redhat
Redhat build Keycloak
Redhat red Hat Single Sign On
Weaknesses CWE-347
CPEs cpe:/a:redhat:build_keycloak:
cpe:/a:redhat:red_hat_single_sign_on:7
Vendors & Products Redhat
Redhat build Keycloak
Redhat red Hat Single Sign On
References
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}


Projects

Sign in to view the affected projects.

cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-11-07T15:39:27.366Z

Reserved: 2026-10-27T13:49:55.445Z

Link: CVE-2026-117691

cve-icon Vulnrichment

Updated: 2026-11-05T16:28:29.946Z

cve-icon NVD

Status : Undergoing Analysis

Published: 2026-11-05T14:17:01.320

Modified: 2026-11-07T16:16:39.990

Link: CVE-2026-117691

cve-icon Redhat

Severity : Important

Publid Date: 2026-11-05T00:00:00Z

Links: CVE-2026-117691 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-11-05T17:00:09Z

Weaknesses