Vulnerability 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.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Freescout | Freescout | < 1.8.207 |
Related Weaknesses (CWE)
References
- https://github.com/freescout-help-desk/freescout/commit/f7bc16c56a6b13c06da52ad5Patch
- https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-5gpc-6ExploitMitigationVendor Advisory
- https://www.ox.security/blog/freescout-rce-cve-2026-28289/ExploitVendor Advisory
FAQ
What is CVE-2026-28289?
CVE-2026-28289 is a vulnerability with a CVSS score of 10.0 (CRITICAL). 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 f...
How severe is CVE-2026-28289?
CVE-2026-28289 has been rated CRITICAL with a CVSS base score of 10.0/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-28289?
Check the references section above for vendor advisories and patch information. Affected products include: Freescout Freescout.