livewire-markdown-editor has arbitrary file upload that allows stored XSS via attachment handler

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.1 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

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 FILESYSTEMDISK 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…

Published by the source

4 May 2026, 22:11 UTC

Last modified by the source

4 May 2026, 22:11 UTC

Source last checked

26 Oct 2026, 14:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-gxxh-8vcj-w2mh

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# Patch Next advisory brief: GHSA-gxxh-8vcj-w2mh

Advisory: livewire-markdown-editor has arbitrary file upload that allows stored XSS via attachment handler
IDs: GHSA-gxxh-8vcj-w2mh
Record: https://patchnext.com/advisories/ghsa-gxxh-8vcj-w2mh (revision 1, source checked 26 Oct 2026, 14:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mckenziearts/livewire-markdown-editor 1.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist mckenziearts/livewire-markdown-editor: affected < 1.3; fixed in 1.3

## Suggested inspection (read-only)
- Packagist mckenziearts/livewire-markdown-editor: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mckenziearts/livewire-markdown-editor.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-gxxh-8vcj-w2mh (GitHub-reviewed advisory GHSA-gxxh-8vcj-w2mh lists affected ranges: Packagist mckenziearts/livewire-markdown-editor >=0 <1.3)

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