A flaw was found in the SAML 1.1 assertion parser of Keycloak, a tool used for identity and access management. The issue occurs when the parser handles a specific element called AuthorityBinding within an authentication statement. Due to an incomplete fix for a previous vulnerability, the parser can enter an infinite loop that consumes all available memory, causing the entire Keycloak service to crash and become unavailable to users.

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Fixes

Solution

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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 advance parser state past AuthorityBinding elements during SAML 1.1 AuthenticationStatement processing in keycloak-saml-core to halt unbounded heap allocation: upgrade to Keycloak 26.4.17, 26.6.8 (or the fixed Rhbk/Keycloak Rhel/Keycloak Services builds), which advance the parser past AuthorityBinding child elements during SAML 1.1 AuthenticationStatement processing, closing all 2 injection vectors (crafted SAML request to realm SAML endpoint, crafted SAML request to SAML identity provider broker endpoint). Until patched, this is a concern on Keycloak deployments exposing realm SAML endpoints or SAML identity provider broker endpoints, so Restrict network access to Keycloak realm SAML endpoints and SAML identity provider broker endpoints to trusted networks and identity providers. As a compensating measure, Configure systemd WatchdogSec and Restart directives to automatically restart Keycloak following JVM OutOfMemoryError termination and Monitor cgroup memory.events and PSI metrics to detect anomalous memory pressure and rapid heap exhaustion. These controls limit blast radius and contain exploitation, but they do not fix the underlying SAML 1.1 parser infinite loop defect — apply the upstream patch to fully remediate. Highest-impact CME: CME-1204 Service Watchdog and Automatic Restart (systemd WatchdogSec/Restart) (medium)

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 19:15:00 +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 16:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in the SAML 1.1 assertion parser of Keycloak, a tool used for identity and access management. The issue occurs when the parser handles a specific element called AuthorityBinding within an authentication statement. Due to an incomplete fix for a previous vulnerability, the parser can enter an infinite loop that consumes all available memory, causing the entire Keycloak service to crash and become unavailable to users.
Title Keycloak-services: keycloak-services: unauthenticated jvm termination via saml 1.1 authoritybinding parsing loop
First Time appeared Redhat
Redhat build Keycloak
Redhat red Hat Single Sign On
Weaknesses CWE-835
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': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-11-06T19:55:21.249Z

Reserved: 2026-10-15T05:36:55.655Z

Link: CVE-2026-110931

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-11-05T17:17:37.280

Modified: 2026-11-06T17:17:13.240

Link: CVE-2026-110931

cve-icon Redhat

Severity : Important

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

Links: CVE-2026-110931 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-11-05T19:00:18Z

Weaknesses