High 8.1Published Jun 25, 2026

CVE-2026-11800Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion

Updated under an hour ago (Oct 28, 2026, 2:10 AM ET)

Does this affect you?

It affects Red Hat build of Keycloak 26.6 and 4 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for Red Hat build of Keycloak 26.6

Exploited in the last 30 days

A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature verification. By forging an assertion, the attacker can create unauthorized access tokens. This enables the attacker to impersonate any federated user linked to the affected Identity Provider, leading to unauthorized access and potential privilege escalation.

CVSS: 8.1 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE): CWE-347
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: redhat
NVD analysis: Analyzed
Record last updated: Jul 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Red Hat Red Hat build of Keycloak 26.6 redhat:build_keycloak	from 26.6.4-2 not affected	CNA record
Red Hat Red Hat Data Grid 8 redhat:jboss_data_grid	8	CNA record
Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack redhat:jbosseapxp	Versions not stated	CNA record
Red Hat Red Hat Single Sign-On 7 redhat:red_hat_single_sign_on	7	CNA record
Red Hat Red Hat build of Keycloak 26.6 redhat:build_keycloak	from 26.6.4-2 not affected	CISA ADP
Red Hat Red Hat Data Grid 8 redhat:jboss_data_grid	8	CISA ADP
Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack redhat:jbosseapxp	Versions not stated	CISA ADP
Red Hat Red Hat Single Sign-On 7 redhat:red_hat_single_sign_on	7	CISA ADP
redhat build_of_keycloak redhat:build_of_keycloak	from 26.6 before 26.6.4	NVD

References

References

https://access.redhat.com/errata/RHSA-2026:30083	vendor-advisory, x-refsource-redhat
https://access.redhat.com/errata/RHSA-2026:30084	vendor-advisory, x-refsource-redhat
https://access.redhat.com/security/cve/CVE-2026-11800	vdb-entry, x-refsource-redhat, vendor-advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2487006	issue-tracking, x-refsource-redhat, vendor-advisory
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-11800.json	vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.