dbcve.org
KeycloakApplication · Redhat

CVE-2020-1727

MEDIUM · 5.4 CVSS v3.1 Published 2020-06-22
Fix available
A fix is available. Upgrade to 9.0.2 or later.
See remediation →
60/100
Remediation priority · Elevated
Remotely reachable 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 vulnerability was found in Keycloak before 9.0.2, where every Authorization URL that points to an IDP server lacks proper input validation as it allows a wide range of characters. This flaw allows a malicious to craft deep links that introduce further attack scenarios on affected clients.

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 before version 9.0.2 contains an input validation vulnerability in the Authorization URL endpoint for Identity Provider (IDP) servers. The lack of proper input validation allows a wide range of characters to be accepted, enabling attackers to craft malicious deep links that can introduce further attack scenarios against affected clients.

MitigationUpgrade Keycloak to version 9.0.2 or later which contains the fix for proper input validation on Authorization URLs. For systems that cannot immediately upgrade, implement additional input validation filters on IDP authorization endpoints as a compensating control.

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:< 9.0.2

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
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/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 version
    Check the installed Keycloak version by reviewing the release notes, build artifacts, or the version displayed in the Keycloak admin console (typically found in the Server Info section or footer). Compare the version number to the affected range: any version before 9.0.2 is vulnerable.
    Affected if The installed Keycloak version is 9.0.1, 9.0.0, or any earlier version.
  2. Confirm Identity Provider (IDP) is configured
    Log into the Keycloak admin console and navigate to the Identity Provider section. Review the list of configured identity providers. The vulnerability exists in the Authorization URL endpoint specifically for IDP servers.
    Affected if At least one Identity Provider is added and enabled in Keycloak.
  3. Verify IDP Authorization endpoint is accessible
    Check that the IDP Authorization URL endpoint is reachable. This typically involves confirming that the IDP configuration includes an authorization URL and that clients can initiate authentication flows through this endpoint.
    Affected if The IDP is configured with an authorization URL that accepts user authentication requests.
  4. Review IDP authorization URL input handling
    Inspect the IDP configuration in Keycloak for how the authorization URL is constructed and validated. The vulnerability allows a wide range of characters to be accepted in the authorization URL parameter without proper validation.
    Affected if The IDP authorization endpoint accepts and processes URL parameters without strict input validation controls.

You are affected if your Keycloak version is before 9.0.2 AND you have any Identity Provider configured that uses the Authorization URL endpoint.

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
Upgrade available Upgrade to 9.0.2 or later
Fixed in 9.0.2
Interim mitigation

Upgrade Keycloak to version 9.0.2 or later which contains the fix for proper input validation on Authorization URLs. For systems that cannot immediately upgrade, implement additional input validation filters on IDP authorization endpoints as a compensating control.

Fix this in Keycloak 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
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2020-1727 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2020-1727 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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