CVE-2026-9796: Keycloak server Keycloak Has A Time-of-check Time-of-use Vulnerability

MODERATE
Advisory Identifier: GHSA-pq65-77rc-7r8c
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CVSS 6.5
CWE-367
Published
Advisory Summary

CVE-2026-9796 is a MODERATE (CVSS 6.5) keycloak has a time-of-check time-of-use vulnerability (CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition) affecting Keycloak server libraries in the Maven ecosystem. The issue involves keycloak has a time-of-check time-of-use (toctou) race condition. Remediation is available by upgrading affected packages to version 26.6.4.

CVE-2026-9796 at a Glance

CVE Identifier CVE-2026-9796
GHSA Identifier GHSA-pq65-77rc-7r8c
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition
Affected Product Keycloak server
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 6.5

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

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

How to Fix CVE-2026-9796

To remediate this vulnerability, upgrade all affected Keycloak server 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-server fixed: 26.6.4 
<dependency>
    <groupId>org.keycloak</groupId>
    <artifactId>keycloak-server</artifactId>
    <version>26.6.4</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-2026-9796, 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 server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 26.6.4), 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-367: Time-of-check Time-of-use (TOCTOU) Race Condition, where the product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. In Keycloak server, 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. An authenticated administrator with the `manage-clients` role can exploit a Time-of-check to time-of-use (TOCTOU) vulnerability in the name-based admin role checks. This allows the attacker to escalate their privileges to `realm-admin` for all users within the realm, granting them extensive control over the system. The composite role relationship persists even after the attacker's own permissions are revoked and across system reboots.

CVE-2026-9796 Affected Keycloak server Versions

1 component(s)
Fixed Versions:
26.6.4
Product / Package Ecosystem Affected Versions Fixed Version
org.keycloak:keycloak-server
maven/org.keycloak/keycloak-server
Maven
< 26.6.4
26.6.4

References

NVD — CVE-2026-9796 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-9796
Keycloak server Source Repository REPOSITORY
https://github.com/keycloak/keycloak/issues/49427
Keycloak server Source Repository REPOSITORY
https://github.com/keycloak/keycloak/pull/49624
Security Fix Commit FIX COMMIT
https://github.com/keycloak/keycloak/commit/39cb8de54c8517efeda4baa8bc314fd40e9c6934
access.redhat.com/errata/rhsa-2026:56... WEB
https://access.redhat.com/errata/RHSA-2026:56523
access.redhat.com/errata/rhsa-2026:56... WEB
https://access.redhat.com/errata/RHSA-2026:56524
Keycloak server Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-9796
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2482464
Keycloak server Source Repository REPOSITORY
https://github.com/keycloak/keycloak

Frequently Asked Questions

What is CVE-2026-9796?
CVE-2026-9796 is a security vulnerability in Keycloak server involving Keycloak has a Time-of-check Time-of-use (TOCTOU) Race Condition under CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition.
Which Keycloak server versions are affected?
Affected versions include releases prior to 26.6.4 across affected packages: org.keycloak:keycloak-server.
What version fixes CVE-2026-9796?
Upgrading to 26.6.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is keycloak-server affected?
Yes, org.keycloak:keycloak-server is affected in releases prior to 26.6.4. Upgrade your dependency to 26.6.4 or later.
What is the CVSS score of CVE-2026-9796?
CVE-2026-9796 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-9796?
CVE-2026-9796 is classified under CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition (The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.).
How can I check Maven dependencies for CVE-2026-9796?
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-pq65-77rc-7r8c",
  "modified" : "2026-08-19T00:31:09Z",
  "published" : "2026-05-28T06:31:09Z",
  "aliases" : [ "CVE-2026-9796" ],
  "summary" : "Keycloak has a Time-of-check Time-of-use (TOCTOU) Race Condition",
  "details" : "A flaw was found in Keycloak. An authenticated administrator with the `manage-clients` role can exploit a Time-of-check to time-of-use (TOCTOU) vulnerability in the name-based admin role checks. This allows the attacker to escalate their privileges to `realm-admin` for all users within the realm, granting them extensive control over the system. The composite role relationship persists even after the attacker's own permissions are revoked and across system reboots.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.keycloak:keycloak-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "26.6.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-9796"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/issues/49427"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/pull/49624"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/commit/39cb8de54c8517efeda4baa8bc314fd40e9c6934"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:56523"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:56524"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-9796"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2482464"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/keycloak/keycloak"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-367" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-01T21:24:41Z",
    "nvd_published_at" : "2026-05-28T05:16:41Z"
  }
}