Vulnerability-Lookup

CVE-2026-50188 (GCVE-0-2026-50188)

Vulnerability from cvelistv5 – Published: 2026-07-09 18:44 – Updated: 2026-07-09 19:20

Title

Kirby: Request header injection in `Http\Remote`

Summary

Kirby is an open-source content management system. Prior to 4.9.4 and 5.4.4, Kirby sites and plugins using the Kirby Http Remote class, including Remote::request(), Remote::get(), and Remote::post(), to send outgoing HTTP requests with untrusted data in the headers option could allow newline characters in a header value to inject a separate unintended request header to the remote service. This issue is fixed in versions 4.9.4 and 5.4.4.

Severity

6.9 (Medium)


                        
                          CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-09 19:18 UTC

CWE

CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')
CWE-113 - Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')

Assigner

GitHub_M mitre root

References

5 references

URL	Tags
https://github.com/getkirby/kirby/security/adviso…	x_refsource_CONFIRM
https://github.com/getkirby/kirby/commit/aa33414e…	x_refsource_MISC
https://github.com/getkirby/kirby/commit/fad9cbd2…	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

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FKIE_CVE-2026-50188

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

Severity

6.9 (Medium) - CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/getkirby/kirby/commit/aa33414e1669e866cdd6f4decfae2a669e8bb828
	security-advisories@github.com	https://github.com/getkirby/kirby/commit/fad9cbd22c73ed0fbd3aaf62310a8dcacfc007cd
	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-4v4h-m2qq-ppgw

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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          "product": "kirby",
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    }
  ],
  "id": "CVE-2026-50188",
  "lastModified": "2026-07-10T15:49:19.093",
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          "baseScore": 6.9,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
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          "modifiedAttackComplexity": "NOT_DEFINED",
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    },
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}

GHSA-4V4H-M2QQ-PPGW

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

Summary

Kirby: Request header injection in `Http\Remote`

Details

TL;DR

This vulnerability affects Kirby sites and plugins that use the Kirby\Http\Remote class (including Remote::request(), Remote::get(), Remote::post(), and similar helpers) to send outgoing HTTP requests and that pass untrusted, user-controlled data into the headers option of such a request.

By including newline characters in the value of the header, it was possible to inject a separate, independent header that was not intended to be set.

A successful attack requires that an application or plugin forwards attacker-influenced input into a request header value. Sites that only send static, developer-defined headers are not affected. The attack does not target Panel users or site visitors directly; it targets the remote service that Kirby connects to.

In Kirby's default configuration, the Remote class is not exposed to untrusted input, so a default installation is not affected. The vulnerability becomes relevant for custom code, plugins, or integrations that build request headers from user input.

Introduction

HTTP header injection (also known as CRLF injection) is a type of vulnerability that allows an attacker to insert additional, attacker-controlled HTTP headers into a request or response. HTTP headers are separated by carriage-return and line-feed characters (\r\n). If untrusted data containing these characters is placed into a header value without sanitization, an attacker can terminate the intended header early and append headers of their own.

For outgoing requests, this means an attacker who controls part of a header value can add or override headers that the application did not intend to send. Depending on the remote service, this can be used to override security-relevant headers (such as Authorization, Host, or Cookie), to smuggle requests, or to poison caches on the upstream system.

Such vulnerabilities are relevant if untrusted input can reach the header values of an outgoing request – for example, a user-configurable API token, a forwarded tracking identifier, or any other value that originates from a request, form field, or content file.

Affected components

The Kirby\Http\Remote class is used throughout Kirby and by plugins to perform outgoing HTTP requests. Its headers option allows callers to define the headers sent with the request.

As the vulnerability is in the way Remote assembles these headers, it affects all code paths that send a Remote request whose header values contain untrusted data. The Kirby core itself has not passed untrusted data in that way, but plugins or custom code might have used the class in such a way.

Impact

In affected releases, header values passed to Remote were handed to the cURL request library without removing newline characters:

The headers option accepted arbitrary strings as header values and forwarded them to the underlying cURL request unchanged. A value containing \r\n was written verbatim to the socket and therefore split into several header lines on the wire.

For example, a single X-Foo header value of "Bar\r\nX-Injected: pwned" produced two separate headers in the outgoing request:

X-Foo: Bar
X-Injected: pwned

The receiving server parsed X-Injected: pwned as its own header. In the same way, an attacker could override a header that the application set earlier in the same request (for example, replacing a legitimate Authorization header).

The vulnerability allows attackers to inject or override HTTP headers in outgoing requests, provided the affected application or plugin includes attacker-controlled data in a header value.

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 now strip carriage-return and line-feed characters from header values before they are passed to the underlying request, preventing additional headers from being injected.

Severity

6.9 (Medium)


                  
                    CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N

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{
  "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-2026-50188"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-113",
      "CWE-93"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-18T15:04:46Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### TL;DR\n\nThis vulnerability affects Kirby sites and plugins that use the `Kirby\\Http\\Remote` class (including `Remote::request()`, `Remote::get()`, `Remote::post()`, and similar helpers) to send outgoing HTTP requests and that pass untrusted, user-controlled data into the `headers` option of such a request.\n\nBy including newline characters in the value of the header, it was possible to inject a separate, independent header that was not intended to be set.\n\nA successful attack requires that an application or plugin forwards attacker-influenced input into a request header value. Sites that only send static, developer-defined headers are *not* affected. The attack does not target Panel users or site visitors directly; it targets the remote service that Kirby connects to.\n\nIn Kirby\u0027s default configuration, the `Remote` class is not exposed to untrusted input, so a default installation is *not* affected. The vulnerability becomes relevant for custom code, plugins, or integrations that build request headers from user input.\n\n----\n\n### Introduction\n\nHTTP header injection (also known as CRLF injection) is a type of vulnerability that allows an attacker to insert additional, attacker-controlled HTTP headers into a request or response. HTTP headers are separated by carriage-return and line-feed characters (`\\r\\n`). If untrusted data containing these characters is placed into a header value without sanitization, an attacker can terminate the intended header early and append headers of their own.\n\nFor outgoing requests, this means an attacker who controls part of a header value can add or override headers that the application did not intend to send. Depending on the remote service, this can be used to override security-relevant headers (such as `Authorization`, `Host`, or `Cookie`), to smuggle requests, or to poison caches on the upstream system.\n\nSuch vulnerabilities are relevant if untrusted input can reach the header values of an outgoing request \u2013 for example, a user-configurable API token, a forwarded tracking identifier, or any other value that originates from a request, form field, or content file.\n\n### Affected components\n\nThe `Kirby\\Http\\Remote` class is used throughout Kirby and by plugins to perform outgoing HTTP requests. Its `headers` option allows callers to define the headers sent with the request.\n\nAs the vulnerability is in the way `Remote` assembles these headers, it affects all code paths that send a `Remote` request whose header values contain untrusted data. The Kirby core itself has not passed untrusted data in that way, but plugins or custom code might have used the class in such a way.\n\n### Impact\n\nIn affected releases, header values passed to `Remote` were handed to the cURL request library without removing newline characters:\n\nThe `headers` option accepted arbitrary strings as header values and forwarded them to the underlying cURL request unchanged. A value containing `\\r\\n` was written verbatim to the socket and therefore split into several header lines on the wire.\n\nFor example, a single `X-Foo` header value of `\"Bar\\r\\nX-Injected: pwned\"` produced two separate headers in the outgoing request:\n\n```\nX-Foo: Bar\nX-Injected: pwned\n```\n\nThe receiving server parsed `X-Injected: pwned` as its own header. In the same way, an attacker could override a header that the application set earlier in the same request (for example, replacing a legitimate `Authorization` header).\n\nThe vulnerability allows attackers to inject or override HTTP headers in outgoing requests, provided the affected application or plugin includes attacker-controlled data in a header value.\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 now strip carriage-return and line-feed characters from header values before they are passed to the underlying request, preventing additional headers from being injected.",
  "id": "GHSA-4v4h-m2qq-ppgw",
  "modified": "2026-06-18T15:04:47Z",
  "published": "2026-06-18T15:04:46Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/getkirby/kirby/security/advisories/GHSA-4v4h-m2qq-ppgw"
    },
    {
      "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:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Kirby: Request header injection in `Http\\Remote`"
}

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-2026-50188 (GCVE-0-2026-50188)

FKIE_CVE-2026-50188

GHSA-4V4H-M2QQ-PPGW

TL;DR

Introduction

Affected components

Impact

Patches

Tags

Sightings

Nomenclature

Related by attack behaviour