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Single Sign OnApplication · Redhat

CVE-2017-12158

MEDIUM · 5.4 CVSS v3.0 Published 2017-10-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

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
It was found that Keycloak would accept a HOST header URL in the admin console and use it to determine web resource locations. An attacker could use this flaw against an authenticated user to attain reflected XSS via a malicious server.

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 · high confidence

Keycloak admin console accepted user-supplied HOST header values to determine web resource locations, enabling reflected XSS. An attacker could inject malicious scripts via a crafted HOST header that would be reflected back to authenticated users when they access the admin console.

MitigationConfigure Keycloak to use a fixed, trusted base URL for web resources rather than trusting the incoming HOST header. Validate and sanitize all host header inputs in the admin console.

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
Single Sign OnApplication
Affected:= 7.0= 7.1
KeycloakApplication
Affected:all versions

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
Low
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.0/AV:N/AC:L/PR:L/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 RHSSO installation
    Search for Keycloak directories or check running Java processes for keycloak or rh-sso patterns. Common locations: /opt/keycloak, /opt/rh/sso, or check systemctl services.
    Affected if Keycloak or Red Hat Single Sign-On is installed and running.
  2. Determine installed version
    Check version file in the Keycloak/RHSSO installation directory, or run: ls -la <install_dir>/modules/system/layers/base/org/keycloak/keycloak-server/main/ or check the RPM package with rpm -qi keycloak-server or rh-sso-7.1
    Affected if Version is 7.0 or 7.1 for RHSSO, or any version for upstream Keycloak.
  3. Verify admin console is accessible
    Attempt to access the admin console at /auth/admin/ or /admin/ relative to your base URL. The vulnerability only affects authenticated admin console users.
    Affected if The admin console is exposed and users authenticate to it.
  4. Check for trusted base URL configuration
    Inspect the standalone.xml, standalone-ha.xml, or domain.xml configuration files for the <web-context> setting or any base URL configuration. Look for explicit <host> or <base-url> settings versus relying on incoming request headers.
    Affected if No fixed base URL is configured and the application derives URLs from the incoming HOST header.
  5. Inspect HOST header handling in configuration
    Review the undertow or jboss web subsystem in the configuration XML for any rewrite valves or host header validation. Check if the server trusts the Host header without validation.
    Affected if The server configuration trusts and uses the client-supplied HOST header for constructing resource URLs.

You are affected if Keycloak or RHSSO is running with the admin console exposed and no fixed trusted base URL is configured, allowing the HOST header to determine web resource locations.

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

Configure Keycloak to use a fixed, trusted base URL for web resources rather than trusting the incoming HOST header. Validate and sanitize all host header inputs in the admin console.

Fix this in Single Sign On Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2017-12158 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
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