GHSA-GXXH-8VCJ-W2MH

Vulnerability from github – Published: 2026-05-04 22:11 – Updated: 2026-05-04 22:11
VLAI?
Summary
livewire-markdown-editor has arbitrary file upload that allows stored XSS via attachment handler
Details

Impact

All versions of mckenziearts/livewire-markdown-editor prior to v1.3 contain a critical arbitrary file upload vulnerability in the MarkdownEditor::updatedAttachments() Livewire handler. The handler calls $file->store() with no server-side validation of MIME type, extension, or file content.

Any authenticated user with access to a page embedding <livewire:markdown-editor> can upload files of any type (.html, .svg, .js, .php, .exe, etc.) to the disk configured by livewire-markdown-editor.disk. When that disk is a public cloud bucket (S3, DigitalOcean Spaces, Cloudflare R2, Scaleway Object Storage — the common configuration when FILESYSTEM_DISK points to such a disk), uploaded files are served publicly with a guessed Content-Type header.

The consequences include:

  • Stored XSS on the storage domain via uploaded .html or .svg files
  • Phishing page hosting on the application's own storage domain (trust laundering)
  • Malware distribution from a domain users associate with the application
  • Markdown injection in the editor output via crafted filenames (the client-supplied getClientOriginalName() value was inserted verbatim into the markdown)

A real-world exploitation of this vulnerability was observed in production on a community platform using this package.

Patches

Upgrade to v1.3 or later.

Workarounds

If developers cannot upgrade immediately, disable the upload UI on every instance of the editor by passing :show-upload="false":

  <livewire:markdown-editor wire:model="content" :show-upload="false" />

This hides the file input and prevents the vulnerable code path from being reached.

Resources

  • Patch commit: https://github.com/mckenziearts/livewire-markdown-editor/pull/12
  • Release: https://github.com/mckenziearts/livewire-markdown-editor/releases/tag/v1.3
  • CWE-434: https://cwe.mitre.org/data/definitions/434.html
  • CWE-79: https://cwe.mitre.org/data/definitions/79.html
Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "mckenziearts/livewire-markdown-editor"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-434",
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-04T22:11:05Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Impact\nAll versions of `mckenziearts/livewire-markdown-editor` prior to **v1.3** contain a critical arbitrary file upload vulnerability in the `MarkdownEditor::updatedAttachments()` Livewire handler. The handler calls `$file-\u003estore()` with no server-side validation of MIME type, extension, or file content.\n\nAny authenticated user with access to a page embedding `\u003clivewire:markdown-editor\u003e` can upload files of any type (`.html`, `.svg`, `.js`, `.php`, `.exe`, etc.) to the disk configured by `livewire-markdown-editor.disk`. When that disk is a public cloud bucket (S3, DigitalOcean Spaces, Cloudflare R2, Scaleway Object Storage \u2014 the common configuration when `FILESYSTEM_DISK` points to such a disk), uploaded files are served publicly with a guessed `Content-Type` header.\n\nThe consequences include:\n\n- **Stored XSS** on the storage domain via uploaded `.html` or `.svg` files\n- **Phishing page hosting** on the application\u0027s own storage domain (trust laundering)\n- **Malware distribution** from a domain users associate with the application\n- **Markdown injection** in the editor output via crafted filenames (the client-supplied `getClientOriginalName()` value was inserted verbatim into the markdown)\n\nA real-world exploitation of this vulnerability was observed in production on a community platform using this package.\n\n### Patches\n\nUpgrade to **v1.3** or later.\n\n### Workarounds\n\nIf developers cannot upgrade immediately, disable the upload UI on every instance of the editor by passing `:show-upload=\"false\"`:\n\n```blade\n  \u003clivewire:markdown-editor wire:model=\"content\" :show-upload=\"false\" /\u003e\n```\n\nThis hides the file input and prevents the vulnerable code path from being reached.\n\n### Resources\n\n- Patch commit: https://github.com/mckenziearts/livewire-markdown-editor/pull/12\n- Release: https://github.com/mckenziearts/livewire-markdown-editor/releases/tag/v1.3\n- CWE-434: https://cwe.mitre.org/data/definitions/434.html\n- CWE-79: https://cwe.mitre.org/data/definitions/79.html",
  "id": "GHSA-gxxh-8vcj-w2mh",
  "modified": "2026-05-04T22:11:05Z",
  "published": "2026-05-04T22:11:05Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/mckenziearts/livewire-markdown-editor/security/advisories/GHSA-gxxh-8vcj-w2mh"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mckenziearts/livewire-markdown-editor/commit/1e60eaa5781e89704e112425f832774be85cd71f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/mckenziearts/livewire-markdown-editor"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mckenziearts/livewire-markdown-editor/releases/tag/v1.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "livewire-markdown-editor has arbitrary file upload that allows stored XSS via attachment handler"
}


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Sightings

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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.


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