Vulnerability-Lookup

CVE-2026-49276 (GCVE-0-2026-49276)

Vulnerability from cvelistv5 – Published: 2026-07-09 18:48 – Updated: 2026-07-10 14:11

Title

Kirby: Self cross-site scripting (self-XSS) in the writer field

Summary

Kirby is an open-source content management system. Prior to 4.9.4 and 5.4.4, Kirby sites using the writer field in any blueprint allowed a scripting link to be included as the target of a link or email link in writer mark components, making the target clickable by the user who entered it and enabling self cross-site scripting in the Panel. This issue is fixed in versions 4.9.4 and 5.4.4.

Severity

7.4 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-10 14:11 UTC

CWE

CWE-83 - Improper Neutralization of Script in Attributes in a Web Page

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/getkirby/kirby/security/adviso…	x_refsource_CONFIRM
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-2026-49276

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

Severity

7.4 (High) - CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/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/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-rhj6-r49h-5932

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "kirby",
          "vendor": "getkirby",
          "versions": [
            {
              "status": "affected",
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    }
  ],
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GHSA-RHJ6-R49H-5932

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

Summary

Kirby: Self cross-site scripting (self-XSS) in the writer field

Details

TL;DR

This vulnerability affects Kirby sites that use the writer field in any blueprint.

It was possible to include a scripting link as the target of a link (or email link). This link target would then be clickable by the user who entered it.

A successful attack commonly requires knowledge of the content structure by the attacker as well as social engineering of a user with access to the Panel. The attack cannot be automated.

In Kirby's default configuration, the vulnerability is limited to self-XSS and cannot directly affect other users or visitors of the site. Panel plugins that are directly using the <k-writer> component may also be affected by stored XSS if they don't sanitize the resulting HTML before saving it to the content.

This vulnerability is of high severity for affected sites.

Introduction

Cross-site scripting (XSS) is a type of vulnerability that allows attackers to execute any kind of JavaScript code inside the Panel session of the same or other users. In the Panel, a harmful script can, for example, trigger requests to Kirby's API with the permissions of the victim.

Self cross-site scripting (self-XSS) typically involves a user inadvertently executing malicious code within their own context, often through social engineering techniques. This can occur when a user is tricked into pasting and executing malicious JavaScript code into the browser's developer console, address bar or form fields.

In a stored XSS attack, the malicious payload is saved into the content data and has the potential to affect other users or site visitors.

Such vulnerabilities are critical if you might have potential attackers in your group of authenticated Panel users. They can escalate their privileges if they get access to the Panel session of an admin user. Depending on your site, other JavaScript-powered attacks are possible.

Affected components

The writer field allows users to input formatted text, including links to arbitrary URLs and email addresses. Its link and email marks are therefore a target for XSS attacks.

As the vulnerability is in the writer mark components, it also affects all uses of the <k-writer> component in Panel plugins.

Impact

In affected releases, the link and email marks did not prevent XSS payloads from being submitted to the writer field's content data:

The link mark allowed users to enter JavaScript URLs using the "custom" URL type. These URLs would already be sanitized by the backend before storing the malicious link in the content file. However, the link may be clicked by the same user who entered it before the content is saved.
The email mark was also vulnerable to injected JavaScript URLs. However, it was not possible to perform the attack via the Panel user interface due to email validation. The attack needed to be performed via a side channel such as the browser console.

The vulnerability allows attackers to inject malicious links into content. If the authenticated user clicked such a link before saving the content, the malicious script code would then be executed in their browser.

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 have added more robust validation against dangerous URL schemes that are entered in the affected writer marks.

Severity

7.4 (High)


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

Show details on source website

JSON

To clipboard

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  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.9.3"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "getkirby/cms"
      },
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          "events": [
            {
              "introduced": "0"
            },
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              "fixed": "4.9.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
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        "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-2026-49276"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-83"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-18T15:04:41Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### TL;DR\n\nThis vulnerability affects Kirby sites that use the writer field in any blueprint.\n\nIt was possible to include a scripting link as the target of a link (or email link). This link target would then be clickable by the user who entered it.\n\nA successful attack commonly requires knowledge of the content structure by the attacker as well as social engineering of a user with access to the Panel. The attack *cannot* be automated.\n\nIn Kirby\u0027s default configuration, the vulnerability is limited to self-XSS and *cannot* directly affect other users or visitors of the site. Panel plugins that are directly using the `\u003ck-writer\u003e` component may also be affected by stored XSS if they don\u0027t sanitize the resulting HTML before saving it to the content.\n\n**This vulnerability is of high severity for affected sites.**\n\n----\n\n### Introduction\n\nCross-site scripting (XSS) is a type of vulnerability that allows attackers to execute any kind of JavaScript code inside the Panel session of the same or other users. In the Panel, a harmful script can, for example, trigger requests to Kirby\u0027s API with the permissions of the victim.\n\n*Self* cross-site scripting (self-XSS) typically involves a user inadvertently executing malicious code within their own context, often through social engineering techniques. This can occur when a user is tricked into pasting and executing malicious JavaScript code into the browser\u0027s developer console, address bar or form fields.\n\nIn a *stored* XSS attack, the malicious payload is saved into the content data and has the potential to affect other users or site visitors.\n\nSuch vulnerabilities are critical if you might have potential attackers in your group of authenticated Panel users. They can escalate their privileges if they get access to the Panel session of an admin user. Depending on your site, other JavaScript-powered attacks are possible.\n\n### Affected components\n\nThe `writer` field allows users to input formatted text, including links to arbitrary URLs and email addresses. Its `link` and `email` marks are therefore a target for XSS attacks.\n\nAs the vulnerability is in the writer mark components, it also affects all uses of the `\u003ck-writer\u003e` component in Panel plugins.\n\n### Impact\n\nIn affected releases, the `link` and `email` marks did not prevent XSS payloads from being submitted to the writer field\u0027s content data:\n\n- The `link` mark allowed users to enter JavaScript URLs using the \"custom\" URL type. These URLs would already be sanitized by the backend before storing the malicious link in the content file. However, the link may be clicked by the same user who entered it before the content is saved.\n- The `email` mark was also vulnerable to injected JavaScript URLs. However, it was not possible to perform the attack via the Panel user interface due to email validation. The attack needed to be performed via a side channel such as the browser console.\n\nThe vulnerability allows attackers to inject malicious links into content. If the authenticated user clicked such a link before saving the content, the malicious script code would then be executed in their browser.\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 have added more robust validation against dangerous URL schemes that are entered in the affected writer marks.",
  "id": "GHSA-rhj6-r49h-5932",
  "modified": "2026-06-18T15:04:41Z",
  "published": "2026-06-18T15:04:41Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/getkirby/kirby/security/advisories/GHSA-rhj6-r49h-5932"
    },
    {
      "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:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Kirby: Self cross-site scripting (self-XSS) in the writer field"
}

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.
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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-2026-49276 (GCVE-0-2026-49276)

FKIE_CVE-2026-49276

GHSA-RHJ6-R49H-5932

TL;DR

Introduction

Affected components

Impact

Patches

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