CVE-2026-53593 File upload in freescout
Authenticated attackers can upload .pht web shells to execute arbitrary commands due to an incomplete file extension denylist.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-53593?
CVE-2026-53593 is a high-severity vulnerability in freescout-help-desk freescout, published on 20 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to version 1.8.224, the denylist that neutralizes dangerous file uploads (`Helper::$restricted_extensions`) is incomplete: it does not cover the `.pht` extension. The authenticated upload endpoint `POST /uploads/upload` (`SecureController@upload`) stores files with their original extension into the web-accessible directory `storage/app/public/uploads/` (served at `/storage/uploads/`). On the standard Apache + `libapache2-mod-php` deployment, the default handler `<FilesMatch ".+\.ph(ar|p[3457]?|t|tml)$">` executes `.pht`, so **any authenticated agent can upload a `.pht` web shell and run arbitrary commands as the web-server user** (`www-data`). This is a direct bypass of the fix for CVE-2025-48471, which added `phtml`/`phar` but not `pht` (nor `phtm`, `phps`). Version 1.8.224 contains an updated fix.
Weakness: CWE-434
Which versions are affected by CVE-2026-53593?
How do I fix CVE-2026-53593?
No fix has been published for CVE-2026-53593 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-53593 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53593 exists.
Sources
Also known as GHSA-27vp-fpg8-j8wv.