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    CVE-2026-11800

    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.

    Published:Jun 25, 2026
    Last Modified:Jun 26, 2026
    EPS:Jun 25, 2026
    EPSS Score:0.0019
    CVSS Score:8.1

    Affected Products

    Vendor
    Redhat
    Product
    Build Keycloak
    Vendor
    Redhat
    Product
    Build Of Keycloak
    Vendor
    Redhat
    Product
    Data Grid
    Vendor
    Redhat
    Product
    Jboss Data Grid
    Vendor
    Redhat
    Product
    Jboss Enterprise Application Platform Expansion Pack
    Vendor
    Redhat
    Product
    Jbosseapxp
    Vendor
    Redhat
    Product
    Red Hat Single Sign On

    Exploits

    No exploit reference

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-463 Padding Oracle Crypto Attack
    CAPEC-475 Signature Spoofing by Improper Validation

    Related CVEs

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    CVE-2026-19729 (CVSS 4.9) — A flaw was found in the key provider component of the keycloak-services library, which is the core engine for …
    CVE-2026-17615 (CVSS 7.5) — A flaw was found in RESTEasy's SourceProvider. This vulnerability allows an unauthenticated attacker to perfor…
    CVE-2026-82968 (CVSS 6.4) — A flaw was found in the first-broker-login flow of the Keycloak identity management service. When a user links…
    CVE-2026-19611 (CVSS 7.4) — A flaw was found in WildFly Elytron. Password hashing and verification normalize input with Unicode NFKC, whic…
    CVE-2026-15571 (CVSS 7.3) — A flaw was found in the legacy client-initiated account-linking endpoint of Keycloak, a widely used open-sourc…
    CVE-2026-79652 (CVSS 5.9) — A flaw was found in the JWT Bearer authorization grant implementation within the keycloak-services component o…
    CVE-2026-18963 (CVSS 9.1) — A flaw was found in the reset-credentials flow of the keycloak-services component, which is the core engine fo…
    CVE-2026-19608 (CVSS 5.3) — A flaw was found in the group policy provider of Keycloak authorization services, which is used to manage fine…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High