Vulnerability · Published Mar 3, 2026 · Assigned by GitHub_M
CVE-2026-28289FreeScout 1.8.206 Patch Bypass for CVE-2026-27636 via Zero-Width Space Character Leads to Remote Code Execution
Critical 10.0
In plain English
A critical-severity unrestricted file upload in freescout from freescout-help-desk. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 35.1% (higher than 98% of all known vulnerabilities). Ready-made attack tooling exists: Metasploit, public proof-of-concept code.
Official description
FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. A patch bypass vulnerability for CVE-2026-27636 in FreeScout 1.8.206 and earlier allows any authenticated user with file upload permissions to achieve Remote Code Execution (RCE) on the server by uploading a malicious .htaccess file using a zero-width space character prefix to bypass the security check. The vulnerability exists in the sanitizeUploadedFileName() function in app/Http/Helper.php. The function contains a Time-of-Check to Time-of-Use (TOCTOU) flaw where the dot-prefix check occurs before sanitization removes invisible characters. This vulnerability is fixed in 1.8.207.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| freescout-help-desk | freescout | < 1.8.207 |
Weakness: CWE-434 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H