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Build Of KeycloakApplication · Redhat

CVE-2026-4366

MEDIUM · 5.8 CVSS v3.1 Published 2026-03-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
67/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A flaw was identified in Keycloak, an identity and access management solution, where it improperly follows HTTP redirects when processing certain client configuration requests. This behavior allows an attacker to trick the server into making unintended requests to internal or restricted resources. As a result, sensitive internal services such as cloud metadata endpoints could be accessed. This issue may lead to information disclosure and enable attackers to map internal network infrastructure.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Keycloak improperly follows HTTP redirects when processing client configuration requests, allowing attackers to trick the server into making requests to internal/restricted resources such as cloud metadata endpoints. This is a Server-Side Request Forgery (SSRF) vulnerability that enables information disclosure and internal network mapping.

MitigationApply the vendor patch for Keycloak when available, and implement network segmentation to restrict server access to metadata endpoints and internal services.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Build Of KeycloakApplication
Affected:all versions
Jboss Enterprise Application PlatformApplication
Affected:= 8.0.0
Jboss Enterprise Application Platform Expansion PackApplication
Affected:all versions
Single Sign OnApplication
Affected:= 7.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
None
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Keycloak or JBoss EAP installation and version
    Check for Keycloak installation directories (typically /opt/keycloak or /opt/jboss/keycloak) and locate the version file (VERSION or keycloak_VERSION). For JBoss EAP, check /opt/jbossas/standalone/configuration or use 'rpm -qa | grep keycloak' or 'rpm -qa | grep jboss' commands.
    Affected if The installed version matches any of the affected products: Redhat Build Of Keycloak (all versions), JBoss EAP 8.0.0, JBoss EAP Expansion Pack (all versions), or RH SSO 7.0.
  2. Verify client registration service is enabled
    Inspect the Keycloak/JBoss configuration file (standalone.xml or keycloak.conf) and search for 'clientRegistration' or 'client-registration' settings. Also check if the Client Registration Service endpoint at /auth/realms/{realm}/client-registration/ is accessible.
    Affected if Client registration service is enabled and publicly accessible without additional restrictions.
  3. Check for redirect-following behavior in logs
    Review Keycloak server logs (typically in /opt/keycloak/standalone/log/ as server.log or boot.log) for patterns like 'Following redirect' or HTTP 3xx responses during client registration operations. Search for client-registration API calls.
    Affected if Logs show HTTP redirects being followed to non-standard or internal URLs during client configuration requests.
  4. Inspect network accessibility to metadata endpoints
    From the Keycloak/JBoss server, verify if internal cloud metadata endpoints are reachable by testing connectivity to common metadata IPs such as 169.254.169.254 (AWS/Azure/GCP) or internal network ranges. Use curl or nmap from the server to probe these endpoints.
    Affected if The Keycloak server can successfully reach cloud metadata endpoints or internal network resources that should be restricted.
  5. Audit client registration configurations
    Review registered clients in the Keycloak admin console or database for any clients with redirect URIs pointing to internal endpoints. Check client templates or client scopes for custom redirect configurations.
    Affected if Client configurations contain redirect URIs pointing to internal IP ranges (127.0.0.1, 169.254.x.x, 10.x.x.x, 192.168.x.x) or cloud metadata services.

You are affected if you run any version of Redhat Build of Keycloak, JBoss EAP 8.0.0, JBoss EAP Expansion Pack, or RH SSO 7.0 with client registration service enabled and the server can reach internal network resources.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor patch for Keycloak when available, and implement network segmentation to restrict server access to metadata endpoints and internal services.

Fix this in Build Of Keycloak Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-4366 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data