FreeScout is an open-source help desk and shared inbox system built on PHP's Laravel framework. Versions prior to 1.8.206 contain a vulnerability (CVE-2026-27636) due to insufficient file upload restrictions in the Helper.php file, specifically the failure to block uploads of .htaccess and .user.ini files. These files are critical in Apache web server environments because they control directory-level configuration, including URL rewriting, access control, and execution directives. When Apache is configured with AllowOverride All, which is common, uploaded .htaccess files can override server settings. An authenticated attacker can upload a malicious .htaccess file that redefines how the server processes files, enabling remote code execution (RCE). This allows the attacker to execute arbitrary code on the server with the privileges of the web server process. The vulnerability does not require user interaction beyond authentication and can be exploited remotely over the network. It can also be chained with CVE-2026-27637 for potentially greater impact. The vulnerability is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type). The CVSS v3.1 base score is 8.8, indicating high severity, with attack vector network, low attack complexity, privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. The issue was publicly disclosed on February 25, 2026, and fixed in FreeScout version 1.8.206.

The impact of CVE-2026-27636 is severe for organizations using vulnerable FreeScout versions on Apache servers with AllowOverride All enabled. An attacker with valid credentials can upload malicious .htaccess files to execute arbitrary code remotely, potentially leading to full system compromise. This can result in data theft, unauthorized access to sensitive help desk tickets and customer information, service disruption, and lateral movement within the network. Since FreeScout is often used by customer support teams, compromise could expose sensitive customer data and internal communications, damaging organizational reputation and violating data protection regulations. The vulnerability affects confidentiality, integrity, and availability, making it a critical risk for organizations relying on FreeScout for support operations. Exploitation does not require user interaction beyond authentication, increasing the likelihood of successful attacks if credentials are compromised or weak. The ability to chain this vulnerability with CVE-2026-27637 may further escalate privileges or persistence.

Organizations should immediately upgrade FreeScout to version 1.8.206 or later, where the vulnerability is patched. If upgrading is not immediately possible, administrators should implement the following mitigations: 1) Restrict file upload types explicitly to exclude .htaccess, .user.ini, and other potentially dangerous files at the application level. 2) Harden Apache configurations by limiting or disabling AllowOverride directives, ideally setting AllowOverride None to prevent .htaccess files from overriding server settings. 3) Implement strict access controls and monitoring on upload directories to detect and prevent unauthorized file uploads. 4) Enforce strong authentication mechanisms and monitor for suspicious login activity to reduce risk of credential compromise. 5) Use web application firewalls (WAFs) to detect and block malicious upload attempts. 6) Conduct regular security audits and penetration testing focused on file upload functionalities. 7) Educate users about the risks of credential sharing and phishing to reduce the chance of attacker authentication.