freescout-help-desk freescout up to 1.8.206 .htaccess sanitizeUploadedFileName unrestricted upload

Summaryinfo

A vulnerability classified as critical has been found in freescout-help-desk freescout up to 1.8.206. Affected by this issue is the function sanitizeUploadedFileName of the component .htaccess Handler. This manipulation causes unrestricted upload. This vulnerability appears as CVE-2026-28289. The attack may be initiated remotely. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in freescout-help-desk freescout up to 1.8.206. It has been declared as critical. Affected by this vulnerability is the function sanitizeUploadedFileName of the component .htaccess Handler. The manipulation with an unknown input leads to a unrestricted upload vulnerability. The CWE definition for the vulnerability is CWE-434. The product allows the attacker to upload or transfer files of dangerous types that can be automatically processed within the product's environment. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-28289 since 02/26/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1608.002 for this issue.

Upgrading to version 1.8.207 eliminates this vulnerability. Applying the patch f7bc16c56a6b13c06da52ad51fd666546b40818f is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Vendor

• freescout-help-desk

Name

• freescout

Version

• 1.8.206

License

• open-source

Website

• Product: https://github.com/freescout-help-desk/freescout/

CPE 2.3info

• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Discussion