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TI-2026-22596 Aliases CVE-2026-28289

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

Priority HIGH 74CWE-434Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-434.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.35103 98th percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by NVD
Fix Fixed freescout (freescout-help-desk): 1.8.207

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
freescout-help-deskfreescoutbefore 1.8.2071.8.207Patch availableCNA
  • freescout Vendorfreescout-help-desk Affected before 1.8.207 Fixed in 1.8.207 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:freescout:freescout:*:*:*:*:*:*:*:*before 1.8.207Vulnerablefreescout-help-desk
  • cpe:2.3:a:freescout:freescout:*:*:*:*:*:*:*:* Versions before 1.8.207 Vulnerable ·freescout-help-desk

Remediation

  • Fix · CNA freescout (freescout-help-desk) Fixed in 1.8.207

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-28289
  2. 2026-10-25 EPSS moved to the 95th–99th percentile
  3. 2026-10-25 Priority changed: MEDIUM → HIGH

References

Exploit 2

Patch 1

  • TI-2026-22019 FreeScout's Predictable Authentication Token Enables Account Takeover CVSS 3.1CRITICAL 9.8
  • TI-2026-29249 FreeScout has Authentication Bypass and Information Disclosure in SystemController via /system/cron CVSS 4.0HIGH 8.9
  • TI-2026-29247 FreeScout has Predictable Attachment Token that Allows Unauthenticated Private File Download via Brute Force CVSS 4.0HIGH 8.8
  • TI-2026-25245 FreeScout: Stored XSS via Unescaped Email Template Rendering ({!! $thread->body !!}) CVSS 3.1CRITICAL 9.3
  • TI-2024-19354 FreeScout OS Command Injection vulnerability CVSS 3.1CRITICAL 9.1
  • TI-2026-22018 FreeScout: Missing .htaccess in Restricted File Extensions Allows Remote Code Execution on Apache CVSS 3.1HIGH 8.8
See all 45 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences