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KeycloakApplication · Redhat

CVE-2023-6927

MEDIUM · 6.1 CVSS v3.1 Published 2023-12-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges

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 found in Keycloak. This issue may allow an attacker to steal authorization codes or tokens from clients using a wildcard in the JARM response mode "form_post.jwt" which could be used to bypass the security patch implemented to address CVE-2023-6134.

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's JARM (JWT-secured Authorization Response Mode) implementation has a flaw where clients configured with wildcards in the 'form_post.jwt' response mode may improperly validate or process authorization responses. This allows an attacker to potentially intercept or steal authorization codes or tokens by exploiting the wildcard matching behavior, bypassing the fix for CVE-2023-6134.

MitigationUpdate Keycloak to the latest patched version and review all client configurations to ensure wildcards in JARM response modes are properly scoped and validated.

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
KeycloakApplication
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
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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 RH-SSO installation version
    Locate the Keycloak or Red Hat Single Sign-On installation and run 'kc.sh --version' or check the server logs/version file. For RH-SSO 7.0, check the server startup output.
    Affected if The installed version is any version of Red Hat Keycloak or RH-SSO 7.0, as all versions are affected.
  2. Determine if JARM is enabled
    Review the realm settings in the Keycloak admin console under 'Authentication' > 'Authentication flows' or inspect the client configuration for the 'form_post.jwt' response mode.
    Affected if Any realm or client is configured to use JARM with the 'form_post.jwt' response mode.
  3. Locate clients using form_post.jwt response mode
    In the Keycloak admin console, navigate to each client > 'Settings' > 'Advanced Settings' and check the 'Response Mode' dropdown, or query the realm clients via the admin REST API for 'form_post.jwt' in response modes.
    Affected if Any client is configured with 'form_post.jwt' as the response mode.
  4. Inspect for wildcard patterns in JARM configuration
    Review the client's JARM configuration for any wildcard characters in the 'form_post.jwt' or related response mode settings. Check client adapter configurations and realm-level JARM settings.
    Affected if The JARM response mode configuration contains wildcard patterns that could enable improper matching.

A user is affected if they have any version of Keycloak or RH-SSO 7.0 running with clients configured to use JARM 'form_post.jwt' response mode containing wildcard patterns.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update Keycloak to the latest patched version and review all client configurations to ensure wildcards in JARM response modes are properly scoped and validated.

Recommended fix Moderate confidence

Upgrade to the latest Keycloak stable release (22.x or later) or apply the Red Hat Security Patch for RH-SSO 7.0 as specified in the relevant RHSA

  1. 1. Identify your current Keycloak or Red Hat Single Sign On version using the server administration console or command line
  2. 2. Review the Red Hat security advisory (RHSA) associated with this CVE on access.redhat.com for your specific product version
  3. 3. Download or access the fixed version of Keycloak/Red Hat SSO as specified in the security advisory
  4. 4. Back up your current Keycloak configuration, database, and realm data
  5. 5. Stop the running Keycloak or SSO service
  6. 6. Install the patched version following standard upgrade procedures
  7. 7. Verify the JARM response mode configuration does not use wildcards in client redirect URIs
  8. 8. Restart the service and test authentication flows to confirm the fix is applied
Caveat Review release notes for version-specific changes; ensure custom themes/extensions are compatible with the target version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Keycloak Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2023-6927 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