CVE-2026-40591
FreeScout: Improper Authorization in Phone Conversation Creation Enables Cross-Mailbox Hidden Customer Modification
Description
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.
INFO
Published Date :
April 21, 2026, 5:16 p.m.
Last Modified :
April 21, 2026, 6:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-40591
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update FreeScout to version 1.8.214 or later.
- Verify customer visibility controls are enforced.
- Review agent permissions and access scopes.
- Limit creation of phone conversations.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-40591.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-40591 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-40591
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-40591 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-40591 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Apr. 21, 2026
Action Type Old Value New Value Added Reference https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-9ff4-mmhv-x6jp -
New CVE Received by [email protected]
Apr. 21, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N Added CWE CWE-639 Added Reference https://github.com/freescout-help-desk/freescout/commit/83eea1ca47d97c6cdc90c501734bc2579b014a34 Added Reference https://github.com/freescout-help-desk/freescout/releases/tag/1.8.214 Added Reference https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-9ff4-mmhv-x6jp