What is CVE-2026-28289?

CVE-2026-28289 is a critical-severity vulnerability in Freescout, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 10.0/10. Published 2026-03-03.

How severe is CVE-2026-28289?

Critical severity. CVSS v3 base score is 10.0 out of 10.

Is CVE-2026-28289 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Arbitrary file upload in Freescout

CVE-2026-28289

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.

Vulnerability class: Unrestricted File Upload

Published 2026-03-03 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.026 (84.5th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 85th percentile — 84.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.311 · newest: 0.026 · change: -0.286

Affected products

Freescout
Freescout-Help-Desk Freescout — versions < 1.8.207

Weakness classification (CWE)

CWE-434 — Unrestricted Upload of File with Dangerous Type

Public proof-of-concept exploits

References

github.com/freescout-help-desk/freescout/security/advisories/GHSA-5gpc-65p8-ffwp (Exploit, Mitigation, Vendor Advisory)
github.com/freescout-help-desk/freescout/commit/f7bc16c56a6b13c06da52ad51fd6665… (Patch)
af854a3a-2127-422b-91ae-364da2661108 (Exploit, Vendor Advisory)

Frequently asked questions

What is CVE-2026-28289?: CVE-2026-28289 is a critical-severity vulnerability in Freescout, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 10.0/10. Published 2026-03-03.
How severe is CVE-2026-28289?: Critical severity. CVSS v3 base score is 10.0 out of 10.
Is CVE-2026-28289 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.