# CVE-2026-28289: FreeScout 1.8.206 Patch Bypass for CVE-2026-27636 via Zero-Width Space Character Leads to Remote Code Execution

> Authenticated users can achieve remote code execution by uploading a malicious .htaccess file using zero-width space characters to bypass security checks.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Mar 2026
- **Updated:** 5 Mar 2026
- **Also known as:** GHSA-5gpc-65p8-ffwp

## What is CVE-2026-28289?

CVE-2026-28289 is a critical vulnerability in freescout-help-desk freescout, published on 3 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-434 (Unrestricted Upload of File with Dangerous Type)

## Which versions are affected by CVE-2026-28289?

It affects 1 product.


Products: Freescout Freescout.

## How do I fix CVE-2026-28289?

No fix has been published for CVE-2026-28289 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-28289 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-28289 exists.

Public exploit code:

- CVE-2026-28289 (github_poc): https://github.com/0xredash/CVE-2026-28289
- FreeScout Unauthenticated RCE via ZWSP .htaccess Bypass (metasploit)

## Other vulnerabilities in freescout-help-desk freescout

- [CVE-2026-27637](https://insights.sbomify.com/CVE-2026-27637/): FreeScout's Predictable Authentication Token Enables Account Takeover (critical 9.8)
- [CVE-2026-32754](https://insights.sbomify.com/CVE-2026-32754/): FreeScout: Stored XSS via Unescaped Email Template Rendering ({!! $thread->body !!}) (critical 9.3)
- [CVE-2024-29185](https://insights.sbomify.com/CVE-2024-29185/): FreeScout OS Command Injection vulnerability (critical 9.1)
- [CVE-2026-40498](https://insights.sbomify.com/CVE-2026-40498/): FreeScout has Authentication Bypass and Information Disclosure in SystemController via /system/cron (high 8.9)
- [CVE-2026-40496](https://insights.sbomify.com/CVE-2026-40496/): FreeScout has Predictable Attachment Token that Allows Unauthenticated Private File Download via Brute Force (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-28289 and fix it if it is affected.

What it is: CVE-2026-28289 is a critical vulnerability in freescout-help-desk freescout, published on 3 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-28289 exists.

Affected product: freescout-help-desk freescout. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-28289/ (Markdown: https://insights.sbomify.com/CVE-2026-28289/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28289
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28289
- OSV: https://osv.dev/vulnerability/CVE-2026-28289

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28289/
Summaries are generated and may contain mistakes; the official description above is the record.