CVE-2026-28289

CRITICAL 10.0

FreeScout 1.8.206 Patch Bypass for CVE-2026-27636 via Zero-Width Space Character Leads to Remote Code Execution

CVSS Score

10.0

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-434
Vendor	freescout-help-desk
Product	freescout
Published	Mar 3, 2026
Last Updated	Mar 5, 2026

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CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Affected Versions

freescout-help-desk / freescout

< 1.8.207

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-5gpc-65p8-ffwp github.com: https://github.com/freescout-help-desk/freescout/commit/f7bc16c56a6b13c06da52ad51fd666546b40818f ox.security: https://www.ox.security/blog/freescout-rce-cve-2026-28289/