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CWE-454Weakness · CWE-454

CVE-2026-54003

CRITICAL · 9.1 CVSS v4.0 Published 2026-07-09
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available 7 weeks old

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
Kirby is an open-source content management system. Prior to 4.9.4 and from 5.4.4, Kirby sites with no configured user accounts that run on publicly accessible servers behind a reverse proxy setting the Forwarded, X-Client-IP, or X-Real-IP request header could allow remote attackers to install the Panel and create the first admin user because local-IP checks trusted those headers incorrectly. This issue is fixed in versions 4.9.4 and 5.4.4.

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

Kirby CMS versions prior to 4.9.4 and 5.4.4 contain an authentication bypass vulnerability where reverse proxy headers (Forwarded, X-Client-IP, X-Real-IP) are incorrectly trusted during local-IP validation. On publicly accessible sites with no configured user accounts, this allows remote attackers to access the Panel installation wizard and create the first admin user, effectively hijacking the CMS.

MitigationUpgrade to Kirby 4.9.4 or 5.4.4, or ensure user accounts exist before public exposure; also configure reverse proxy to not accept forwarded headers from untrusted sources.

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

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
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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 Kirby CMS version
    Locate the version file in the Kirby installation directory (typically version.php in the system folder or check composer.json), or access the Panel login page which sometimes displays version info in the footer
    Affected if installed version is lower than 4.9.4 or 5.4.4 (versions prior to these releases)
  2. Verify Panel installation wizard accessibility
    Attempt to access the Panel installation wizard endpoint directly (typically /panel/install or /panel/_/install) from an external network location or using curl with a non-localhost origin header
    Affected if the installation wizard returns a valid response instead of redirecting to login or returning an access denied message
  3. Confirm no user accounts exist
    Check the accounts directory (site/accounts/ or similar path depending on Kirby version) for any existing user folders, or query the database if using a database-driven setup
    Affected if no user accounts are configured and the Panel remains in installation-ready state
  4. Inspect reverse proxy header handling
    Examine the Kirby configuration files (site/config/config.php or similar) and web server configuration for directives that process Forwarded, X-Client-IP, or X-Real-IP headers, and verify if these are being trusted for IP validation
    Affected if reverse proxy headers are being processed and trusted for local-IP validation without proper filtering

A user is affected if running a Kirby version prior to 4.9.4/5.4.4 with the Panel installation wizard publicly accessible, no existing user accounts, and reverse proxy headers being trusted for IP validation.

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
Patch available Apply the vendor patch
Vendor patch github.com →
Interim mitigation

Upgrade to Kirby 4.9.4 or 5.4.4, or ensure user accounts exist before public exposure; also configure reverse proxy to not accept forwarded headers from untrusted sources.

Recommended fix High confidence

Kirby 4.9.4 or later for 4.x branches; Kirby 5.4.4 or later for 5.x branches

  1. 1. Identify the currently installed Kirby version by checking the composer.json file or the kirby/composer.json in the vendor directory
  2. 2. If running a 4.x version prior to 4.9.4, plan upgrade to version 4.9.4 or later
  3. 3. If running a 5.x version at 5.4.4 or later (including 5.4.4), plan upgrade to version 5.4.4 or later
  4. 4. Before upgrading, ensure you have a complete backup of the site including database and files
  5. 5. Run composer update getkirby/kirby to upgrade to the latest patch version
  6. 6. Verify the installation works correctly after upgrade
  7. 7. If using a reverse proxy, ensure the fix in commit 1c7fee9 is included in the version you upgrade to
Caveat Review Kirby's release notes for breaking changes between your current version and the target version, as minor version jumps may include template or API changes

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

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the patch applied

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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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-2026-54003 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