GHSA-gxxh-8vcj-w2mh
HIGHlivewire-markdown-editor has arbitrary file upload that allows stored XSS via attachment handler
Blast Radius
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Description
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
.htmlor.svgfiles - 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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | mckenziearts/livewire-markdown-editor | all versions | 1.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mckenziearts/livewire-markdown-editor. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update mckenziearts/livewire-markdown-editor to 1.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-gxxh-8vcj-w2mh is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-gxxh-8vcj-w2mh is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-gxxh-8vcj-w2mh. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-gxxh-8vcj-w2mh in your dependencies?
O3 detects GHSA-gxxh-8vcj-w2mh across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.