CVE-2026-27636
Freescout ≤ 1.8.206
Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2026-27636 is a high-severity Unrestricted Upload of File with Dangerous Type (CWE-434) vulnerability in Freescout Freescout. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 20% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SI-3 (Malicious Code Protection) and CM-7 (Least Functionality) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-27636 is an unrestricted upload vulnerability in FreeScout, an open-source help desk and shared inbox application built on PHP's Laravel framework. In versions prior to 1.8.206, the file upload restriction list implemented in `app/Misc/Helper.php` fails to block `.htaccess` or `.user.ini` files. This allows authenticated users to upload such files to directories on Apache web servers configured with `AllowOverride All`, a common default setting, enabling attackers to override server configurations for malicious purposes. The vulnerability carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) and is associated with CWE-434 (Unrestricted Upload of File with Dangerous Type).
An authenticated user with low privileges, such as a standard help desk ticket submitter, can exploit this remotely over the network with low complexity and no user interaction required. By uploading a crafted `.htaccess` file, the attacker redefines how Apache processes subsequent files, leading to remote code execution (RCE) on the server. This can occur independently or in combination with CVE-2026-27637, potentially granting full server compromise including data exfiltration, privilege escalation, or further lateral movement.
The FreeScout project addressed this in version 1.8.206 by updating the file upload restrictions in `app/Misc/Helper.php` to explicitly block `.htaccess` and `.user.ini` files, as detailed in the project's GitHub security advisories (GHSA-6gcm-v8xf-j9v9 and GHSA-mw88-x7j3-74vc) and the fixing commit (9984071e6f1b4e633fdcffcea82bbebc9c1e009c). Security practitioners should upgrade to 1.8.206 or later, review Apache configurations to limit `AllowOverride` where possible, and audit file upload directories for unauthorized `.htaccess` files.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-8612
Vulnerability Data
FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to version 1.8.206, FreeScout's file upload restriction list in `app/Misc/Helper.php` does not include `.htaccess` or `.user.ini` files. On Apache servers with `AllowOverride All` (a common…
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configuration), an authenticated user can upload a `.htaccess` file to redefine how files are processed, enabling Remote Code Execution. This vulnerability can be exploited on its own or in combination with CVE-2026-27637. Version 1.8.206 fixes both vulnerabilities.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.1.1
Mitigating Controls (NIST 800-53 r5) AI
Malicious-code protection at entry points blocks dangerous file types from being accepted and executed.
Least functionality restricts the file types and automatic processing capabilities the system will accept.
Mobile-code controls define, authorize, and block unacceptable uploaded code before automatic processing occurs.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Restricting execution of unauthorized software directly blocks dangerous uploaded files from running.
Hardened configuration baselines can enforce allowed file types and processing rules.
Secure development practices include input validation and file-type restrictions that prevent this weakness.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Configuration and acceptance testing verify that file-upload handling enforces allowed types and does not permit dangerous content to be stored or executed.
Secure-coding guidelines and security testing explicitly address restrictions on allowed file types and upload handling, reducing the risk that dangerous file uploads are accepted without validation.
Mandated testing for malicious content and known vulnerabilities reduces the likelihood that an outsourced component will contain or accept dangerous file types that could later be uploaded or executed.
Application allow-listing and pre-use scanning of received files directly blocks the introduction of executable content that has not been vetted, eliminating the primary vector for unrestricted dangerous file uploads.