GHSA-gxxh-8vcj-w2mh: Mckenziearts/livewire markdown editor Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-gxxh-8vcj-w2mh",
  "modified" : "2026-05-04T22:11:05Z",
  "published" : "2026-05-04T22:11:05Z",
  "aliases" : [ ],
  "summary" : "livewire-markdown-editor has arbitrary file upload that allows stored XSS via attachment handler",
  "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->store()` with no server-side validation of MIME type, extension, or file content.\n\nAny 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.\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's 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  <livewire:markdown-editor wire:model=\"content\" :show-upload=\"false\" />\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",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "mckenziearts/livewire-markdown-editor"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.3"
      } ]
    } ]
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-434", "CWE-79" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-04T22:11:05Z",
    "nvd_published_at" : null
  }
}