# CVE-2026-40589: FreeScout has Customer Edit Cross-Mailbox Email Takeover

> Low-privileged agents can hijack hidden customer emails and conversations across mailboxes, exposing private data and modifying records.

- **Severity:** High 7.6 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Apr 2026
- **Updated:** 21 Apr 2026
- **Also known as:** GHSA-mv55-3mgv-fxwr

## What is CVE-2026-40589?

CVE-2026-40589 is a high-severity vulnerability in freescout-help-desk freescout, published on 21 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.214, a low-privileged agent can edit a visible customer and add an email address already owned by a hidden customer in another mailbox. The server discloses the hidden customer’s name and profile URL in the success flash, reassigns the hidden email to the visible customer, and rebinds hidden-mailbox conversations for that email to the visible customer. Version 1.8.214 fixes the issue.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-40589?


## How do I fix CVE-2026-40589?

No fix has been published for CVE-2026-40589 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-40589 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40589 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40589 and fix it if it is affected.

What it is: CVE-2026-40589 is a high-severity vulnerability in freescout-help-desk freescout, published on 21 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40589 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-2026-40589/ (Markdown: https://insights.sbomify.com/CVE-2026-40589/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40589
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40589
- OSV: https://osv.dev/vulnerability/CVE-2026-40589

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40589/
Summaries are generated and may contain mistakes; the official description above is the record.