CVE-2026-7571: Keycloak Access Token Disclosure And Implicit Vulnerability

HIGH
Advisory Identifier: GHSA-hq3p-w4xv-x7vp
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CVSS 7.1
CWE-472
Published
Advisory Summary

CVE-2026-7571 is a HIGH (CVSS 7.1) access token disclosure and implicit vulnerability (CWE-472: External Control of Assumed-Immutable Web Parameter) affecting Keycloak libraries in the Maven ecosystem. The issue involves access token disclosure and implicit flow bypass via forged client data. Remediation is available by upgrading affected packages to version 26.6.2.

CVE-2026-7571 at a Glance

CVE Identifier CVE-2026-7571
GHSA Identifier GHSA-hq3p-w4xv-x7vp
Severity HIGH
CVSS v3.1 Base Score 7.1
CWE Classification CWE-472: External Control of Assumed-Immutable Web Parameter
Affected Product Keycloak
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-7571

To remediate this vulnerability, upgrade all affected Keycloak dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.keycloak:keycloak-services fixed: 26.6.2 
<dependency>
    <groupId>org.keycloak</groupId>
    <artifactId>keycloak-services</artifactId>
    <version>26.6.2</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=org.keycloak

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-7571, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.keycloak

Analyze the terminal output to locate any version of Keycloak in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 26.6.2), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.keycloak command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-472: External Control of Assumed-Immutable Web Parameter, where the web application does not sufficiently verify inputs that are assumed to be immutable but are actually externally controllable, such as hidden form fields. In Keycloak, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

A flaw was found in Keycloak. A low-privilege user, with knowledge of user credentials and client ID, can bypass a security control intended to disable the implicit flow in OpenID Connect (OIDC) clients. By manipulating client data during a session restart, an attacker can obtain an access token that should not be available. This vulnerability can also lead to the exposure of these access tokens in server logs, proxy logs, and HTTP Referrer headers, resulting in sensitive information disclosure.

CVE-2026-7571 Affected Keycloak Versions

1 component(s)
Fixed Versions:
26.6.2
Product / Package Ecosystem Affected Versions Fixed Version
org.keycloak:keycloak-services
maven/org.keycloak/keycloak-services
Maven
< 26.6.2
26.6.2

References

NVD — CVE-2026-7571 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-7571
Keycloak Source Repository REPOSITORY
https://github.com/keycloak/keycloak/issues/49110
Keycloak Source Repository REPOSITORY
https://github.com/keycloak/keycloak/pull/49120
Security Fix Commit FIX COMMIT
https://github.com/keycloak/keycloak/commit/56bbfa3d8abccf39df787ae73e044a75aba1da13
access.redhat.com/errata/rhsa-2026:19... WEB
https://access.redhat.com/errata/RHSA-2026:19596
access.redhat.com/errata/rhsa-2026:19... WEB
https://access.redhat.com/errata/RHSA-2026:19597
Keycloak Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-7571
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2464263
Keycloak Source Repository REPOSITORY
https://github.com/keycloak/keycloak
Keycloak Release RELEASE
https://github.com/keycloak/keycloak/releases/tag/26.6.2

Frequently Asked Questions

What is CVE-2026-7571?
CVE-2026-7571 is a security vulnerability in Keycloak involving Access token disclosure and implicit flow bypass via forged client data under CWE-472: External Control of Assumed-Immutable Web Parameter.
Which Keycloak versions are affected?
Affected versions include releases prior to 26.6.2 across affected packages: org.keycloak:keycloak-services.
What version fixes CVE-2026-7571?
Upgrading to 26.6.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is keycloak-services affected?
Yes, org.keycloak:keycloak-services is affected in releases prior to 26.6.2. Upgrade your dependency to 26.6.2 or later.
What is the CVSS score of CVE-2026-7571?
CVE-2026-7571 has a CVSS v3.1 base score of 7.1 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N.
What CWE is associated with CVE-2026-7571?
CVE-2026-7571 is classified under CWE-472: External Control of Assumed-Immutable Web Parameter (The web application does not sufficiently verify inputs that are assumed to be immutable but are actually externally controllable, such as hidden form fields.).
How can I check Maven dependencies for CVE-2026-7571?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.keycloak'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hq3p-w4xv-x7vp",
  "modified" : "2026-06-04T15:36:36Z",
  "published" : "2026-05-19T12:31:42Z",
  "aliases" : [ "CVE-2026-7571" ],
  "summary" : "Keycloak: Access token disclosure and implicit flow bypass via forged client data",
  "details" : "A flaw was found in Keycloak. A low-privilege user, with knowledge of user credentials and client ID, can bypass a security control intended to disable the implicit flow in OpenID Connect (OIDC) clients. By manipulating client data during a session restart, an attacker can obtain an access token that should not be available. This vulnerability can also lead to the exposure of these access tokens in server logs, proxy logs, and HTTP Referrer headers, resulting in sensitive information disclosure.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.keycloak:keycloak-services"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "26.6.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-7571"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/issues/49110"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/pull/49120"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/commit/56bbfa3d8abccf39df787ae73e044a75aba1da13"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:19596"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:19597"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-7571"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2464263"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/keycloak/keycloak"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/releases/tag/26.6.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-472" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-04T15:36:36Z",
    "nvd_published_at" : "2026-05-19T12:16:19Z"
  }
}