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

8.1 / 10

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Description

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.

Basic Information

ID CVE-2026-11800

Source redhat

Published Jun 25, 2026 at 20:57

Affected Product

Vendor Red Hat

Product Red Hat build of Keycloak 26.6

Version 26.6.4-2

CWE Classification

CWE-347

References

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    "published": "2026-06-25T20:57:05.276Z",
    "modified": "2026-06-25T20:57:05.276Z",
    "type": "cve",
    "title": "Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion",
    "source": "redhat",
    "references": "https://access.redhat.com/errata/RHSA-2026:30083\nhttps://access.redhat.com/errata/RHSA-2026:30084\nhttps://access.redhat.com/security/cve/CVE-2026-11800\nhttps://bugzilla.redhat.com/show_bug.cgi?id=2487006",
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