freescout-help-desk freescout up to 1.8.212 Mailbox Connection Settings Endpoint MailboxesController.php connectionIncomingSave access control

Summaryinfo

A vulnerability classified as critical was found in freescout-help-desk freescout up to 1.8.212. This vulnerability affects the function connectionIncomingSave of the file app/Http/Controllers/MailboxesController.php of the component Mailbox Connection Settings Endpoint. Such manipulation leads to access control. This vulnerability is documented as CVE-2026-40569. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, has been found in freescout-help-desk freescout up to 1.8.212. Affected by this issue is the function connectionIncomingSave of the file app/Http/Controllers/MailboxesController.php of the component Mailbox Connection Settings Endpoint. The manipulation with an unknown input leads to a access control vulnerability. Using CWE to declare the problem leads to CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Impacted is confidentiality, integrity, and availability. CVE summarizes:

FreeScout is a free self-hosted help desk and shared mailbox. Versions prior to 1.8.213 have a mass assignment vulnerability in the mailbox connection settings endpoints of FreeScout (`connectionIncomingSave()` at `app/Http/Controllers/MailboxesController.php:468` and `connectionOutgoingSave()` at line 398). Both methods pass `$request->all()` directly to `$mailbox->fill()` without any field allowlisting, allowing an authenticated admin to overwrite any of the 32 fields in the Mailbox model's `$fillable` array -- including security-critical fields that do not belong to the connection settings form, such as `auto_bcc`, `out_server`, `out_password`, `signature`, `auto_reply_enabled`, and `auto_reply_message`. Validation in `connectionIncomingSave()` is entirely commented out, and the validator in `connectionOutgoingSave()` only checks value formats for SMTP fields without stripping extra parameters. An authenticated admin user can exploit this by appending hidden parameters (e.g., `[email protected]`) to a legitimate connection settings save request. Because the `auto_bcc` field is not displayed on the connection settings form (it only appears on the general mailbox settings page), the injection is invisible to other administrators reviewing connection settings. Once set, every outgoing email from the affected mailbox is silently BCC'd to the attacker via the `SendReplyToCustomer` job. The same mechanism allows redirecting outgoing SMTP through an attacker-controlled server, injecting tracking pixels or phishing links into email signatures, and enabling attacker-crafted auto-replies -- all from a single HTTP request. This is particularly dangerous in multi-admin environments where one admin can silently surveil mailboxes managed by others, and when an admin session is compromised via a separate vulnerability (e.g., XSS), the attacker gains persistent email exfiltration that survives session expiry. Version 1.8.213 fixes the issue.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-40569 since 04/14/2026. The exploitation is known to be easy. The attack may be launched remotely. The exploitation needs additional levels of successful authentication. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1068 by the MITRE ATT&CK project.

By approaching the search of inurl:app/Http/Controllers/MailboxesController.php it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 1.8.213 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch f45b9105d43b0352c08fcca154e8ae6177c3d860 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

• freescout-help-desk

Name

• freescout

Version

• 1.8.212

License

• open-source

Website

• Product: https://github.com/freescout-help-desk/freescout/

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