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CVE-2026-40591

7.1 · HIGH

FreeScout is a free self-hosted help desk and shared mailbox.

Published Apr 21, 2026CWE-639EPSS 0.34%

Overview

CVE-2026-40591 is a high-severity vulnerability. It was published on April 21, 2026 and has a CVSS 3.1 base score of 7.1 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.1, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/freescout-help-desk/freescout/commit/83eea1ca47d97c6cdc90c501734bc2579b014a34GitHubgithub.com/freescout-help-desk/freescout/releases/tag/1.8.214GitHubgithub.com/freescout-help-desk/freescout/security/advisories/GHSA-9ff4-mmhv-x6jpGitHubgithub.com/freescout-help-desk/freescout/security/advisories/GHSA-9ff4-mmhv-x6jp

How CyberStrike helps

Frequently asked questions

What is CVE-2026-40591?

CVE-2026-40591 is a high-severity vulnerability. It was published on April 21, 2026 and has a CVSS 3.1 base score of 7.1 (HIGH).

How severe is CVE-2026-40591?

This vulnerability has a CVSS 3.1 base score of 7.1, rated HIGH. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-40591?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-40591?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-40591 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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