CVE-2026-11800

highpriority · track · 0EPSS 0.003 · 23 %ileDEEUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.30% (23rd) EPSS

CVSS 8.1 · high

Is it mine?

6 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · cert_bund · nvd

EPSS · scored 2026-10-27

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

Technical severity, 0–10. One row per scoring source.

8.1

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Nsecondary · ENISA EU

v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Nsecondary · secalert@redhat.com USexploitability 2.8 · impact 5.2

v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Nsecondaryexploitability 2.8 · impact 5.2

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: no · Technical Impact: totalcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-347US

affected products (6)

Products and version ranges known to be affected.

Open Source Keycloakall versionscert_bundDEcpe:/a:keycloak:keycloak:-
Red Hat Enterprise Linuxall versionscert_bundDEcpe:/o:redhat:enterprise_linux:-
Red Hat Red Hat build of Keycloak 26.6< 26.6-8enisa_euvdEU
Red Hat Red Hat build of Keycloak 26.6< 26.6.4-2enisa_euvdEU
redhat build of keycloak26.6 → 26.6.4nvdUScpe:2.3:a:redhat:build_of_keycloak:*:*:*:*:*:*:*:*
Bitnami keycloak26.6.0 → 26.6.4osvUSpkg:bitnami/keycloak

advisories (2)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-2093Keycloak: Mehrere SchwachstellenDeutsch2026-06-25csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Keycloak ausnutzen, um falsche Informationen darzustellen, um Informationen offenzulegen, um einen Cross-Site Scripting Angriff durchzuführen, um Sicherheitsvorkehrungen zu umgehen, und um Dateien zu manipulieren.
BIT-keycloak-2026-11800Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion2026-08-25vendor · osvUS
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.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd cert_bund nvd osv NVD CVE.org MITRE

published 2026-06-25modified 2026-10-25

references (13)

External citations — patches, advisories, analysis.

scry

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