Description
A flaw was found in the SAML identity broker component of Keycloak, which is used to delegate authentication to external identity providers. The issue occurs because the broker fails to verify that a user actually possesses the private key associated with a holder-of-key assertion. An attacker who intercepts a victim signed assertion can replay it to gain unauthorized access and impersonate the victim without needing their private key.
Published: 2026-11-05
Score: 7.4 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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 enforce proof of possession for bound keys in SAML identity broker subject-confirmation validation: upgrade to Keycloak 26.4.17 / 26.6.8 (or the corresponding fixed Red Hat builds), which enforce proof of possession for the bound key or reject assertions that contain only unvalidated holder-of-key confirmations, closing replaying intercepted SAML holder-of-key assertions. Until patched, this is a concern on Keycloak deployments configured as a SAML identity broker trusting upstream providers that issue holder-of-key assertions, so restrict and audit trusted upstream SAML identity providers issuing holder-of-key assertions to prevent interception and unauthorized replay of signed assertions. As a compensating measure, enforce mandatory secondary authentication factor in Keycloak post-federation to block login completion on replayed assertions. These controls limit blast radius and contain exploitation, but they do not fix the underlying missing proof-of-possession verification flaw — apply the upstream patch to fully remediate. Highest-impact CME: CME-801 Multi-Factor Authentication (MFA) (medium)

Tracking

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Advisories

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History

Fri, 06 Nov 2026 17:15:00 +0000


Fri, 06 Nov 2026 10:30:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:build_keycloak: cpe:/a:redhat:build_keycloak:26.4::el9
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 22:30:00 +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 17:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in the SAML identity broker component of Keycloak, which is used to delegate authentication to external identity providers. The issue occurs because the broker fails to verify that a user actually possesses the private key associated with a holder-of-key assertion. An attacker who intercepts a victim signed assertion can replay it to gain unauthorized access and impersonate the victim without needing their private key.
Title Keycloak-services: keycloak-services: saml broker accepts holder-of-key assertions without proof of key possession
First Time appeared Redhat
Redhat build Keycloak
Redhat red Hat Single Sign On
Weaknesses CWE-287
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': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}


Subscriptions

Red Hat Red Hat Build Of Keycloak 26.4
Redhat Build Keycloak Build Of Keycloak Red Hat Single Sign On Single Sign-on
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-11-06T19:44:35.962Z

Reserved: 2026-09-17T04:51:48.112Z

Link: CVE-2026-92855

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-11-05T18:17:10.707

Modified: 2026-11-06T17:20:03.423

Link: CVE-2026-92855

cve-icon Redhat

Severity : Important

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

Links: CVE-2026-92855 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-11-05T22:15:14Z

Weaknesses