freescout-help-desk freescout up to 1.8.213 Conversation customer_id/name/to_email/phone authorization

Summaryinfo

A vulnerability marked as critical has been reported in freescout-help-desk freescout up to 1.8.213. This vulnerability affects unknown code of the component Conversation Handler. This manipulation of the argument customer_id/name/to_email/phone causes authorization. This vulnerability is tracked as CVE-2026-40591. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in freescout-help-desk freescout up to 1.8.213 and classified as critical. Affected by this vulnerability is an unknown code of the component Conversation Handler. The manipulation of the argument customer_id/name/to_email/phone with an unknown input leads to a authorization vulnerability. The CWE definition for the vulnerability is CWE-639. The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

FreeScout is a free self-hosted help desk and shared mailbox. Prior to version 1.8.214, the phone-conversation creation flow accepts attacker-controlled `customer_id`, `name`, `to_email`, and `phone` values and resolves the target customer in the backend without enforcing mailbox-scoped customer visibility. As a result, a low-privileged agent who can create a phone conversation in Mailbox A can bind the new Mailbox A phone conversation to a hidden customer from Mailbox B and add a new alias email to that hidden customer record by supplying `to_email`. Version 1.8.214 fixes the vulnerability.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-40591 since 04/14/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details are known, but no exploit is available.

Upgrading to version 1.8.214 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 83eea1ca47d97c6cdc90c501734bc2579b014a34 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.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• freescout-help-desk

Name

• freescout

Version

• 1.8.213

License

• open-source

Website

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

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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