Vulnerability-Lookup

CVE-2026-54003 (GCVE-0-2026-54003)

Vulnerability from cvelistv5 – Published: 2026-07-09 18:36 – Updated: 2026-07-09 19:23

Title

Kirby: External Initialization of the Panel on reverse proxy setups with the `Forwarded` header

Summary

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.

Severity

9.1 (Critical)


                        
                          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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-09 19:23 UTC

CWE

CWE-454 - External Initialization of Trusted Variables or Data Stores

Assigner

GitHub_M mitre root

References

8 references

URL	Tags
https://github.com/getkirby/kirby/security/adviso…	x_refsource_CONFIRM
https://github.com/getkirby/kirby/pull/8166	x_refsource_MISC
https://github.com/getkirby/kirby/commit/1c7fee90…	x_refsource_MISC
https://github.com/getkirby/kirby/commit/3423f66c…	x_refsource_MISC
https://github.com/getkirby/kirby/commit/66a3a14b…	x_refsource_MISC
https://github.com/getkirby/kirby/commit/ab992dc1…	x_refsource_MISC
https://github.com/getkirby/kirby/releases/tag/4.9.4	x_refsource_MISC
https://github.com/getkirby/kirby/releases/tag/5.4.4	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
getkirby	kirby	Affected: < 4.9.4 Affected: >= 5.0.0, < 5.4.4	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-54003

Vulnerability from fkie_nvd - Published: 2026-07-09 19:17 - Updated: 2026-07-10 15:49

Severity

9.1 (Critical) - 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

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/getkirby/kirby/commit/1c7fee90e49153cf9ca4a6ec17481d25fbedc48d
	security-advisories@github.com	https://github.com/getkirby/kirby/commit/3423f66c01dbc0455862e23ee699d2aa469f3234
	security-advisories@github.com	https://github.com/getkirby/kirby/commit/66a3a14bf0892d320723ba766cd5f1d33a51d15b
	security-advisories@github.com	https://github.com/getkirby/kirby/commit/ab992dc149610b90e337c2955ab6ccb7f72ffb3a
	security-advisories@github.com	https://github.com/getkirby/kirby/pull/8166
	security-advisories@github.com	https://github.com/getkirby/kirby/releases/tag/4.9.4
	security-advisories@github.com	https://github.com/getkirby/kirby/releases/tag/5.4.4
	security-advisories@github.com	https://github.com/getkirby/kirby/security/advisories/GHSA-whxw-24jc-cwmv

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "kirby",
          "vendor": "getkirby",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 4.9.4"
            },
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    }
  ],
  "id": "CVE-2026-54003",
  "lastModified": "2026-07-10T15:49:19.093",
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      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-54003",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-07-09T19:23:16.615569Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-09T19:17:06.120",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/getkirby/kirby/commit/1c7fee90e49153cf9ca4a6ec17481d25fbedc48d"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/getkirby/kirby/commit/3423f66c01dbc0455862e23ee699d2aa469f3234"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/getkirby/kirby/commit/66a3a14bf0892d320723ba766cd5f1d33a51d15b"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/getkirby/kirby/commit/ab992dc149610b90e337c2955ab6ccb7f72ffb3a"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/getkirby/kirby/pull/8166"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/getkirby/kirby/releases/tag/4.9.4"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/getkirby/kirby/releases/tag/5.4.4"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/getkirby/kirby/security/advisories/GHSA-whxw-24jc-cwmv"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-454"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-WHXW-24JC-CWMV

Vulnerability from github – Published: 2026-06-18 15:04 – Updated: 2026-06-18 15:04

Summary

Kirby: External Initialization of the Panel on reverse proxy setups with the `Forwarded` header

Details

TL;DR

This vulnerability affects Kirby sites that have no configured user accounts and are running on publicly accessible servers behind a reverse proxy that sets the Forwarded: for=..., X-Client-IP, or X-Real-IP request header.

It was possible to install the Panel (= create the first admin user) in these setups even from remote IP addresses.

This vulnerability is of critical severity for affected sites.

Your site is not affected if any of the following apply:

An admin account has already been configured
The Panel and API are disabled
The site is not running behind a reverse proxy
The reverse proxy sets the X-Forwarded-For or Client-IP header instead of the affected ones.

Introduction

External Initialization is a type of vulnerability that allows attackers to initialize a system or configuration value without authentication.

This can give untrusted actors access to the system or let them control its behavior.

Affected components

The Kirby Panel and REST API are authenticated by local user accounts. If a Kirby installation does not yet have any users, it first needs to be installed. During the installation process, an initial admin user account is created.

To protect against external initialization attacks that would allow untrusted actors to create an admin user for the Kirby installation, Kirby already checked whether the current request came from a local IP address. This allows installing the Panel in local development setups. Installation on remote servers was only supposed to be possible when the panel.install configuration option was enabled.

The isLocal check takes all relevant request headers into account and treats a request as non-local as soon as any checked request header contains an external IP address.

Impact

In affected releases, the isLocal check for the installation logic did not properly take the Forwarded: for=... header into account. This header is set by modern reverse proxy servers. It also did not take into account the X-Client-IP or X-Real-IP headers, which are set by some custom reverse proxy setups.

This caused Kirby to falsely assume that an installation request was local and allowed creating an admin account even though the reverse proxy forwarded the request from an external IP address.

Reverse proxies setting the X-Forwarded-For or Client-IP headers were not affected. These headers were already properly checked for external IP addresses.

Patches

The problem has been patched in Kirby 4.9.4 and Kirby 5.4.4. Please update to one of these or a later version to fix the vulnerability.

In all of the mentioned releases, we fixed the isLocal check to also properly take Forwarded: for=..., X-Client-IP and X-Real-IP request headers into account.

Workarounds

Sites on older Kirby versions (Kirby 3 starting at 3.7.0) can be protected with one of the following workarounds:

Perform the Panel installation yourself by creating an initial admin account. As soon as one or more accounts are present, the vulnerable installation code is no longer active.
If you don't need the Panel, disable the REST API with the 'api' => false option in config.php.

Credits

Thanks to Peter Levashov (@petersevera) for responsibly reporting the identified issue.

Severity

9.1 (Critical)


                  
                    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

Show details on source website

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To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.9.3"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "getkirby/cms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.9.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.4.3"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "getkirby/cms"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0.0-alpha.1"
            },
            {
              "fixed": "5.4.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54003"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-454"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-18T15:04:57Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### TL;DR\n\nThis vulnerability affects Kirby sites that have no configured user accounts and are running on publicly accessible servers behind a reverse proxy that sets the `Forwarded: for=...`, `X-Client-IP`, or `X-Real-IP` request header.\n\nIt was possible to install the Panel (= create the first admin user) in these setups even from remote IP addresses.\n\n**This vulnerability is of critical severity for affected sites.**\n\nYour site is *not* affected if any of the following apply: \n\n- An admin account has already been configured\n- The Panel and API are disabled\n- The site is not running behind a reverse proxy\n- The reverse proxy sets the `X-Forwarded-For` or `Client-IP` header instead of the affected ones.\n\n----\n\n### Introduction\n\nExternal Initialization is a type of vulnerability that allows attackers to initialize a system or configuration value without authentication.\n\nThis can give untrusted actors access to the system or let them control its behavior.\n\n### Affected components\n\nThe Kirby Panel and REST API are authenticated by local user accounts. If a Kirby installation does not yet have any users, it first needs to be installed. During the installation process, an initial admin user account is created.\n\nTo protect against external initialization attacks that would allow untrusted actors to create an admin user for the Kirby installation, Kirby already checked whether the current request came from a local IP address. This allows installing the Panel in local development setups. Installation on remote servers was only supposed to be possible when the `panel.install` configuration option was enabled.\n\nThe `isLocal` check takes all relevant request headers into account and treats a request as non-local as soon as any checked request header contains an external IP address.\n\n### Impact\n\nIn affected releases, the `isLocal` check for the installation logic did not properly take the `Forwarded: for=...` header into account. This header is set by modern reverse proxy servers. It also did not take into account the `X-Client-IP` or `X-Real-IP` headers, which are set by some custom reverse proxy setups.\n\nThis caused Kirby to falsely assume that an installation request was local and allowed creating an admin account even though the reverse proxy forwarded the request from an external IP address.\n\nReverse proxies setting the `X-Forwarded-For` or `Client-IP` headers were *not* affected. These headers were already properly checked for external IP addresses.\n\n### Patches\n\nThe problem has been patched in [Kirby 4.9.4](https://github.com/getkirby/kirby/releases/tag/4.9.4) and [Kirby 5.4.4](https://github.com/getkirby/kirby/releases/tag/5.4.4). Please update to one of these or a [later version](https://github.com/getkirby/kirby/releases) to fix the vulnerability.\n\nIn all of the mentioned releases, we fixed the `isLocal` check to also properly take `Forwarded: for=...`, `X-Client-IP` and `X-Real-IP` request headers into account.\n\n### Workarounds\n\nSites on older Kirby versions (Kirby 3 starting at 3.7.0) can be protected with one of the following workarounds:\n\n- Perform the Panel installation yourself by creating an initial admin account. As soon as one or more accounts are present, the vulnerable installation code is no longer active.\n- If you don\u0027t need the Panel, disable the REST API with the `\u0027api\u0027 =\u003e false` option in `config.php`.\n\n### Credits\n\nThanks to Peter Levashov (@petersevera) for responsibly reporting the identified issue.",
  "id": "GHSA-whxw-24jc-cwmv",
  "modified": "2026-06-18T15:04:57Z",
  "published": "2026-06-18T15:04:57Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/getkirby/kirby/security/advisories/GHSA-whxw-24jc-cwmv"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/getkirby/kirby"
    },
    {
      "type": "WEB",
      "url": "https://github.com/getkirby/kirby/releases/tag/4.9.4"
    },
    {
      "type": "WEB",
      "url": "https://github.com/getkirby/kirby/releases/tag/5.4.4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Kirby: External Initialization of the Panel on reverse proxy setups with the `Forwarded` header"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-54003 (GCVE-0-2026-54003)

FKIE_CVE-2026-54003

GHSA-WHXW-24JC-CWMV

TL;DR

Introduction

Affected components

Impact

Patches

Workarounds

Credits

Tags

Sightings

Nomenclature

Related by attack behaviour