CVE-2026-40591: CWE-639: Authorization Bypass Through User-Controlled Key in freescout-help-desk freescout
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.
AI Analysis
Technical Summary
CVE-2026-40591 is an authorization bypass vulnerability (CWE-639) in FreeScout help desk software before version 1.8.214. The flaw occurs because the phone-conversation creation process accepts attacker-controlled parameters (customer_id, name, to_email, phone) and resolves the target customer without enforcing mailbox-scoped visibility. Consequently, a low-privileged agent able to create conversations in one mailbox can link those conversations to customers hidden in other mailboxes and add alias emails to those customer records. This breaks intended access controls between mailboxes. The vulnerability has a CVSS 3.1 score of 7.1 (high severity).
Potential Impact
An attacker with low privileges in one mailbox can bypass authorization controls to associate phone conversations with customers from other mailboxes that should be inaccessible. This enables unauthorized modification of customer data, specifically adding new alias emails to hidden customer records, potentially leading to data integrity issues and privacy violations. There is no indication of availability impact or known exploits in the wild.
Mitigation Recommendations
Upgrade FreeScout to version 1.8.214 or later, where this vulnerability is fixed. Since the vendor has released a fixed version, applying this official update is the recommended remediation. Patch status is not explicitly stated but the fix is confirmed in version 1.8.214. No additional mitigation guidance is provided.
CVE-2026-40591: CWE-639: Authorization Bypass Through User-Controlled Key in freescout-help-desk freescout
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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-40591 is an authorization bypass vulnerability (CWE-639) in FreeScout help desk software before version 1.8.214. The flaw occurs because the phone-conversation creation process accepts attacker-controlled parameters (customer_id, name, to_email, phone) and resolves the target customer without enforcing mailbox-scoped visibility. Consequently, a low-privileged agent able to create conversations in one mailbox can link those conversations to customers hidden in other mailboxes and add alias emails to those customer records. This breaks intended access controls between mailboxes. The vulnerability has a CVSS 3.1 score of 7.1 (high severity).
Potential Impact
An attacker with low privileges in one mailbox can bypass authorization controls to associate phone conversations with customers from other mailboxes that should be inaccessible. This enables unauthorized modification of customer data, specifically adding new alias emails to hidden customer records, potentially leading to data integrity issues and privacy violations. There is no indication of availability impact or known exploits in the wild.
Mitigation Recommendations
Upgrade FreeScout to version 1.8.214 or later, where this vulnerability is fixed. Since the vendor has released a fixed version, applying this official update is the recommended remediation. Patch status is not explicitly stated but the fix is confirmed in version 1.8.214. No additional mitigation guidance is provided.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-14T14:07:59.641Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69e7b0e619fe3cd2cde9a4c7
Added to database: 4/21/2026, 5:16:22 PM
Last enriched: 4/21/2026, 5:31:23 PM
Last updated: 4/22/2026, 6:11:21 AM
Views: 10
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