Vulnerability · Published Apr 21, 2026 · Assigned by GitHub_M

CVE-2026-40591FreeScout: Improper Authorization in Phone Conversation Creation Enables Cross-Mailbox Hidden Customer Modification

High 7.1

In plain English

A high-severity authorization bypass via user-controlled key in freescout from freescout-help-desk. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 11% of all known vulnerabilities).

Severity (CVSS 3.1)7.1High

Exploit odds (30 days)0.2%top 88.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
freescout-help-desk	freescout	< 1.8.214

Weakness: CWE-639 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

References

https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-9ff4-mmhv-x6jp x_refsource_CONFIRM
https://github.com/freescout-help-desk/freescout/commit/83eea1ca47d97c6cdc90c501734bc2579b014a34 x_refsource_MISC
https://github.com/freescout-help-desk/freescout/releases/tag/1.8.214 x_refsource_MISC